Curious about Jade appraisal

Recently visited China (Canton, or Guangzhou) and got pressured into
buying two jade bangles. The short story is that I wanted to buy some
Jade, and wanted the two bangles to be cut from the same stone; one
for me and one for a certain other person. I am somewhat naive and
expected US prices of $100 or so each, but was surprised when I had to
negotiate for over two hours to get two bangles for almost 3700RMB
(about $520) and a smallish "gold happiness jade" charm.

I was drawn to the pieces because they clearly are "twins" and they
are whitish with flecks of green. They also have "purple" shadows
when held up to the light; supposedly that is very good and the sales
person used terms like "mature" and "smooth" to sell the virtues of
these pieces.

I am almost certain I was ripped off although the pieces are
supposedly "A" grade, I supposedly have a guarantee (in Chinese, not
even sure what it says), and the dealer is supposedly very
respectable.

How do I find out if these two are worth anything even close to what I
paid? I assumed that buying Jade directly in China would give me
steep discounts; if I paid 3700RMB in China, does that really mean
these two are worth, say, over $2000 back here in the states? I
highly doubt it, I wouldn't buy these for anything like that. Clearly
I'm no expert, however. Even if they appraise for close to the price
I paid in China that would be OK, but again, I highly doubt it as I
see bangles for $100 and much much less.

How can I get a fair appraisal, more for curiosity and learning than
anything else?