If you are shopping on e-bay, there is no reason to avoid BD. Buying a complete bike is always cheaper than building. The only situation in which it makes sense to build is when you already have most the parts or the frame you want is unavailable as a complete bike. This isn't to say that the frame that you are looking at isn't a great deal. We don't know what it is, so it could be. Regardless, this won't be the cheapest way to go.