I'd suggest:

(1) used Borgelt B.40. I'm very pleased with mine.
(2) Tasman V 1000, used if you can find one.

Gotta go with Martin on this one... I've used both and enjoyed them
both. I usually have a slight preference for analog needles over
digital "blocks", but the more I fly the better I get at using my ears
and the seat of my pants; so I find that the Tasman (with its timing
and tone options) is growing to be my favorite.

I have a couple of buddies who love their ILEC SC-7's; but when I
tried to buy one I was told they'd been discontinued due to
calibration problems.

One more note: Good compensation is critical - a poorly compensated
vario (even a high quality one) will seem misleading or cruddy,
especially frustrating when trying to center an important thermal!

Take care,

--Noel