unfortunately, I'm afraid that most potential buyers for BG12's or similar
typically "cheap" gliders are there because they are new to gliding and
looking for a cheap glider...

Well, blush, that's me.

From a financial point of view, I think one is better off
with a "popular" glider. If a glider costs 25-50% less
than a popular Grob 102, 1-34, 1-35, PW-5, Russia, 1-26,
PIK-20, etc, then it seems likely you're not only going
to have a tough time finding parts, insurance, inspections,
but you'd also have a hard time finding someone to buy the
darn thing in the future.

Buying and selling gliders which trade briskly seems a much
better bet. Assuming you sell the glider for the same
money you buy it, the expense is the interest on invested
capital and the higher cost of insurance. There is a
real cost here ($500-1500 yearly). On the other hand you
may have to keep a weirdo glider on the market for a year
to sell it where the higher priced, popular glider sells
in a month.

I know a fine competition pilot who wants to sell his 2-22
and his Duster, but is having trouble finding anyone with
such exotic taste within reasonable towing distance.
Boy I bet he'd like that half of his garage back...

If price is the problem, I'd say get a "popular" glider
in a partnership, syndicate, or club. If you've ever
seen a bunch of women clucking over a newborn, you
know what it'd feel like to be a newly purchased
"popular" glider...