Same decision I have to make every time too Jeff. It's a pain, especially with the prices being down, relatively speaking. I've still got that set of series 2 with the white Sandtrooper plus a Han

and an extra sandtrooper.
Basically I got lazy. I ordered the case from HLJ and it's done. My guess is with enough patience you can end up saving money by going ebay. Even with the chase, mostly because, in my experience, a case is a pretty limited shot at a chase piece. Frankly this stuff is a pain, but I've been able to be less worried about chase pieces simply because most don't matter. Indy was the exception for me. Vader would be too.
I'd have gone with BBTS if they'd had sets again, but since they decided not to, a case was easiest.