What do I do if I bought something and then the seller raised the price and now he won't fulfill my order?

I bought parts for my bike from a companies website, they had these on E-Bay and on there site listed for the same and I got a break by ordering it from his site on shipping (cause I bought more then 1 item). It's been about a month now and still no parts. I checked and he never charged my card, but I did give all the payment info and have the receipts to prove it. What kind of obligation does the business have to fulfill this order? And what if maybe they made a typo or just decided to raise the price, do they still have to honor the listed price at the time I paid? But for whatever reason I go on the site now and the new price is double of what I paid (or was supposed to be charged, since they never charged my card). If he is obligated to fill this order at this price (especially since I talked to him after placing the order and he never said anything was wrong, I verified the prices and everything with him) how do I go about getting this done? Does this fall under that whole truth in advertising and the seller has to honor the lowest listed price?