I found my breeder through bullynet.com. I know it's run by a well-respected, active member of the show community. I'm not sure about their rates, but I'd check them out.
AKC has classifieds too when you register your litter, I used that to get started early on. There are many free sites online to advertise on, but you will get a LOT of calls that waste your time from people wanting a 'cheap' or 'free' bulldog.