Barry said it best... trade for what's "fair".
But maybe this will help a little...

I sort my traders into two lots.
Traders @ face and obsoletes.
The obsoletes are marked with TCR value (C, D, E... whatever) or "price" so at least I and the person I'm trading with have at least some starting point for negotiations.

This year I finally have some "better traders"... chips in the $100 - $400 range... and by showing the "approx value", I think it spares everyone (especially us novices) a little embarrassment of not knowing the trade we proposed was unreasonable.

I know when I'm looking at someone's traders, for some reason, my eyes hone in on the chip worth $500, not $5. (happens EVERY time )
So - on obsoletes, I appreciate seeing a "price" or value upfront. TCR & book values are a "guide" only, but at least I don't have to find out the hard way that the $5 Bucky's house chip I threw on the table wasn't going to cut it.

Hope that helps?