I purchased Marc Chagall Lithograph, "Bezaleel and His Two Golden
Cherubim", which is from his Exodus suite. The picture is in a nice
frame, is numbered, and has a facsimile signature of Chagall. The
certificate lists a printing date of 1993, says that only 500 were
produced, and that the plates were destroyed.

I purchased the lithograph at an auction for $150. Did I over/underpay
and what is the lithograph really worth? Don't be afraid to be blunt,
because I'd rather have a straightforward answer than one that's
sugarcoated.

If you like it, enjoy it!

If you look hard enough, you can usually finds things cheaper some place else.

Auctions are not necessarily the cheapest places on earth.

I am continually surprised at the distortion that occurs at auctions:
some stuff fetches much higher than expected; other much lower.

Nevertheless, it's great fun.

An original edition (1966), signed lithograph from the Exodus suite
would probably sell for at least $10,000. The market in late reprints
of such artists as Chagall, Miro, Dali and Picasso is something of a
jungle, and it is hard to establish any clear objective value for
these prints. Given that your print is nicely framed - and assuming
that framing in the US is as expensive as here in the UK - I would say
the price you paid was fair, and you may have even got something of a
bargain. But you should not expect to be able to resell it for too
much more than you paid.

Have it appraised locally to see what information you can get from that.