Kingsnake and Fauna are good places to start. Also look at available price lists on different breeder sites. The prices fluctuate so you really have to keep an eye on it.
When I went to the Pomona show I picked 6 or 7 morphs I was interested in and averaged the prices from several sources so I would have an idea of the market before I went to the show. Some of the booths were very surprised to see me pull out my phone with my list and prices!