Some really good comments here, most of which I must agree with.
I just finished my 3rd Hill blank. The first one I tried was a Cheetah that cost $275 in 2002. I installed the Connexion Hinge on it and it came out pretty well for a first try, and I figured the most I could lose would be the $275 and I would learn something in the process.
The Tembo blank I got 3 years ago was $400 with carbon, and I finished it as a 1-piece. The Redman I just finished was again with the TD Hinge. It was about $460 with the carbon (the cost of the blanks does keep increasing as time goes by) and the hinge cost almost $100, so I would have been out a bit of cash had I screwed it up - which, fortunately, I didn't.
Moneywise, if you have doubts about your handyman abilities, you are probably better off buying a bow that is finished. If you want to gamble a bit and enjoy taking on a new challenge, it is a great way to get a taste of what bow building is about without the investment of time and money necessary to buy raw materials, forms etc. You just have to approach it from the standpoint that if you mess it up, it was a fun, learning experience.
Personally, I doubt that I will ever buy another finished bow. I truly enjoy the finishing process and particularly like being able to create exactly what I want in terms of fit, draw weight, etc.
I may have just lucked out, because I don't know much about the tillering process, but the last two I finished came out perfectly for my shooting style. I was just careful to sand the same amount of strokes so as not to alter the tiller the way Craig sent it.
The bows I shoot the best and the most are those I have either finished or "customized" in some way, but that is just my experience. The problem I have had in buying either new or used bows has always been that there always seems to be something that doesn't quite fit right and then I'm always reluctant to make any alterations because it will devalue or ruin the bow.