In addition to the references already posted, I'll give a plug for Poloherb's site:
http://www.cryptophysical.com/ As far as value goes, it's very difficult to judge unless it's still being sold by the manufacturer or it's one of the more popular coins (Casascius, Lealana, Ravenbit, etc). Most physical bitcoin varieties tend to have low mintages (100 or less). The price is based on a lot of factors including the condition of the coin, perceived scarcity, reputation of the seller, and the price of bitcoin. For some coins, they come up for sale once in a blue moon so putting an approximate value on it can be nearly impossible.
