The best places would be Aquarium Center (several species usually in stock) and Exotic Aquatics (usually has a few types in stock). Not certain how many House of Tropicals has in stock.
The costs vary depending on the shrimp and the number you buy. Individual costs range from 2-3 dollars up to 9.99 per shrimp. The reds I recently bought at Exotic Aquatics were 6 for 18.99 dollars. You can also check out the following website for some additional shrimp information.
Exotic Aquatics will also extend a 10% discount on livestock purchases to GWAPA members. Just mention it during the check out procedure. EA also has a customer loyaltly program, no charge to enroll, you get a point for every $ spent on both drygoods and livestock. Redeem in increments of $5.100 points is worth $5.
It would be good for us to create ID cards, but thats fodder for another post.