We have been to 2, one yesterday and one a couple months ago. They are alot of fun. Both parties took about an hour.
Yesterdays: the kids could pick any animal with the execption of 2 (higher priced). They each got to pick a sound chip. No clothes. No gift unwrapping (noone here unwraps them at the party, they are always taken home.) Mom gave cupcakes "to go" to each child.
Prior one: Each child picked out whatever animal they wanted. No sound chip or clothes. After the party, everyone went to Chicago Pizza for Pizza and cake.
Build a Bear unually "pairs" with a local resturant. If you look on their web site, you'll see. I've also seen lots of people just set up tables in the food court. Sometimes they buy pizza from a food court vender, sometimes happy meals, sometimes they just bring their own food.
As a host, you have the "right" to decide how much to spend. You can choose just a few bears for the kids to choose from, you can give them each the same bear, whatever you want.
They are alot of fun & if you plan wisely, you can have a great party with out "breaking the bank".