Seed savers exchange has a nice selection of heirloom and hard to source sweet bells. Their catalog is a favorite in our house when it arrives every January.
Most of their seed packs of 50 cost around $3, which is cheap when you consider I've been growing Criolla de Cocina for the last 5 or 6 years. If you're looking for seed deals the best time of year is mid to late summer at whatever local home improvement shop you have near scuba steve - they'll do packs of seeds from Burpee and the like at 3 for $5.
This should be posted in "Vender Vault" where :Review seed and plant vendors. Post praises and/or concerns regarding vendors, their pricing, reliability, and more.