As always, my standard advice about buying homebuilt aircraft remains:
1. Recognize that every builder has different sensibilities and standards of workmanship, and adheres to the designer's plans to a different degree. Some homebuilts make me proud to be a fellow tool-bearing mammal. Others make me feel unsafe just walking under them. Most are somewhere in the middle. Caveat emptor, and your mileage may vary.
2. Have it pre-buy inspected by someone familiar with the type; preferably someone who is familiar with the blueprints and can recognize deviations from the plans. Don't buy an airplane sight-unseen unless you've considered and prepared for the possible worst-case scenarios.
3. Be aware that, if you're not willing and able to work on it yourself, it will likely be no less expensive to own than a factory aircraft. Depending on who you hire to work on it, it could be substantially more expensive.
4. Get familiar with the 14 CFR (or relevant national) rules regarding amateur-built experimentals. The most salient points are: Anybody can work on them; but the annual condition inspection must be signed off by an IA, an A&P, or the holder of the repair(person) certificate.
That said, I'd like to address some of the points that Tim Mara raises in his post on a branch of this thread. For the most part, I tend to agree with him, but I'd like to elaborate a bit on his ideas:
It depends. It took me several years to consistently fly to the edges of my HP-11's potential. Expanding on that, most actual glider _pilots_ have the skills and techniques to handle the average homebuilt sailplane. For most well-established homebuilt designs, the skills and aeronautical knowledge that got you a private pilot rating will probably suffice. Based on what friends have told me, that includes a properly built and tested BG-12. Glider _drivers_ and other sub-par variations on the theme, on the other hand, may find themselves slightly challenged. That said, I allow as that I prefer to see better-than-average piloting skills in HP-18 transitions. The uber-reclined seating, the side-stick, and the Schrederon flaps are three new experiences all at once, and if you get behind the ship late in the game it can be hard to catch up.
Not that we'd expect him to, what with Tim being a big-shot sailplane dealer and all these days...
That's pretty much covered in Part 1 of my standard advice. The good news is that experienced folks can generally tell aircraft materials just by looking at them. The nuts and bolts are yellow cad plated, and the bolts have the X on the head. And in my experience, US sailplane homebuilders generally stick with AN-type hardware since they can get it from AS&S or Wicks for less than nuts and bolts at the local hardware store. Also, many homebuilts are specifically designed with extra strength margins to account for the use of less than top-grade materials. Many such designs actually specify relatively low-grade materials in the plans.
Going off on a tangent, in contrast to the US AN-style aircraft hardware used in most homebuilts, the hardware used in European sailplanes is very hard to grade and identify by inspection. There are many different systems of plating, drive types, head stamps, and thread pitches to deal with.
However, as I've written elsewhere, they have to be inspected by either an A&P or the holder of a prepair[person] certificate. Of which, as I've written elsewhere, I prefer to use the A&P or AI. I continue to believe that anyone who built an airplane cannot view it with the impartiality necessary to inspect it properly.
Yes, the FAA generally takes a hands-off approach to homebuilts. But the same applies to many factory-built European ships licensed as Experimental, Racing and Experimental, Exhibition.
For most experimental types, though, there are type-specific organizations that compile and distribute safety and service bulletins. The HPs, for instance, have a strong network centered on Wayne Paul's Schreder Sailplane Designs Web site. There are several safety and service bulletins on the site, and regular exchanges on the Internet email forum about operational concerns. There are similar Internet fora for the Duster, BG-12, and other designs.
Well, maybe for a while. But assembled out in the elements, a BG would only give a few years of such service.
Thanks, and best regards to all
Bob K.