I was also interested in finding a guide/outfitter for an antelope hunt this fall. What I did was go to the Harrisburg Show where hundreds of outfitters were there to discuss price, services and sucess rates. I am also able to call some of their references and get a feel for the type of hunt I can expect and to get some tips from the guys who have already been there.
I'll be going to Wyoming this Sept for opening week.
By the way, if you intend to hunt antelope in Wyoming, your tag applications must be in by March 15th. Other states may have similar dates.
I am told that if you get tags in an area with large tracks of private land that hunting permission is not hard to obtain. This may be an option that would save you some money.
VH