The BD-5 is a complex high performance aircraft. It is easy to find an original kit for little money. You cannot, however, expect to get a finished aircraft out of an original kit for little money.
It is also difficult to build and a challenge to learn how to fly. Some people have taken more than two decades to complete their original kits. The aircraft is not a forgiving trainer. It demands your full attention at all times while in the air, and will bite you in the rear if you forget to do so. It is also probably one of the most fun aircraft that you will ever fly. Few pilots come out of the cockpit after a flight without an ear-to-ear grin. And to this day, few aircraft attract as much attention at airshows and flight lines around the world as the BD-5.
Contrary to the original advertising materials from Bede Aircraft Co., the original BD-5 kits cannot be assembled, completed and flown by the average Joe Blow without the use of special tools, jigs and procedures and advanced piloting skills. Unless you are highly knowledgeable in the field of aircraft design and construction and have access to a fully-equipped machine shop, you will need third party services in order to complete an original BD-5 kit. No if's, and's or but's about this. The purchase price of an original, unstarted kit only represents the cost of obtaining the very basic materials and components that come with the kit. (In fact, the worst mistake you can make when buying a BD-5 kit is doing so purely on the basis of the asking price.)
For example, without access to the original factory jigs it is extremely difficult to properly trim and align the fuselage components so as to wind up with a straight and true airframe, free of twist. Without a straight and true airframe, you may find it very difficult, if not impossible, to fly the aircraft once it is completed. At the very least you will probably have to make use of various trim tabs at various angles on the control and flight surfaces of the aircraft, and this will detract from the aircraft's performance.
The construction of the wings and flight controls are equally critical. For instance, the horizontal stabilator is composed of two flight control surfaces which are connected through a central spar. If the two halves are not exactly the same and do not balance out, you may have trouble controlling the aircraft. At the very least it will be more difficult to fly.
There are components on the BD-5 which require precision machining, welding and fitting, skills which are well beyond the abilities of the garden-variety experimental aircraft builder. All previously owned kits are always missing some parts, and usually these parts are critical parts that either were not shipped by Bede Aircraft or were sold/given to other builders.
The first BD-5 kits were shipped out in 1974. Since then there have been numerous design changes to the aircraft. Some are optional, some are mandatory safety-of-flight changes that must be made to your kit if you wish to have a safe aircraft. The Bede Aircraft Corp. issued fifteen "Plans Change Notices" or PCN's. In addition, other modifications have been designed for the aircraft by third party companies. These companies also maintain complete libraries of newsletters and bulletins that contain vital historical information necessary for the construction of a safe BD-5.
It is also important to note that the BD-5 is not an aircraft that lends itself well to experimentation with design and construction issues. I know that this statement goes against the very nature of "experimental aviation." You can experiment all you want with that low-and-slow ultralight. The BD-5 is a high performance aircraft. Unless you have assigned a very low value to your life, or have a death wish, experimentation with the design and construction of the BD-5 is not recommended.
The Construction Profile that comes with the BD-5 (the aircraft is not a plans-built aircraft and cannot be built from scratch) is almost always missing Chapter 7 (flight controls installation) and is always missing Chapter 10 (engine and drive system) because Bede Aircraft was never able to come up with a reliable engine/drive system combination. Most sets of plans are usually missing a few pages here and there. Chapter 7, as well as all of the other pages of the plans, is available from the third party companies. Before you cut a single piece of ALCLAD, make sure you have the entire set of pages for the profile. You will have to purchase an engine, drive system and propeller, and these companies supply instructions for installation of these items. If you wish to build a jet, you cannot do so with a standard BD-5 airframe; the additional stresses imposed by the jet engine, as well as its unique internal features, require different construction steps, along with a different recommended wing (17 ft wingspan instead of 21 ft).
The point of saying all of this is not to scare you out of building a BD-5. Quite the contrary, the web site is here to encourage people to build them and to provide information about them. But it is also here to give you a healthy dose of reality and inform you that the BD-5 is not an aircraft that you can build with a minimum of expenditures and effort, or an attitude that if something doesn't work you'll just change it to suit your needs. The BD-5 is a high performance aircraft, and to build the original kits for this aircraft requires assistance from third party companies with specialized tools, jigs, knowledge and experience.
There are two companies currently offering third party services for BD-5 builders. They are BD Micro Technologies and Alturair. Either one of these companies is prepared to offer you the services, parts and documentation that you will need to safely complete your BD-5. I have no vested interests in these companies and receive no compensation for this recommendation. I know Ed "Skeeter" Karnes of BD Micro, and I have personally seen and inspected the high quality of his workmanship. Skeeter is a very dedicated person who truly cares about seeing people build and fly safe BD-5's. His catalog is well worth the asking price. It is not just a catalog, it is concentrated source of education on the history and construction of the BD-5, and in my opinion it is required reading for all potential BD-5 builders. Paul Ross of Alturair has been in the BD-5 business as well for many, many years, and is a great source for those hard-to-find spare parts as well as the complete range of BD-5 construction services.
I collect coins, and in the field of numismatics we have a saying: "Buy the book before you buy the coin." In the BD-5 arena, I think I can safely say that you should buy the BMT catalog before you buy the kit. That investment can easily save you thousands of dollars and plenty of years of frustration. Take my word for it, the BMT catalog is worth every penny.