Depending how much you plan to spend there, they do a "bear bucks" - kind of a frequent shopper program. I think after you spend $100, you get $10 off. But if you have several kids, it may add up to more than that (depending what you allow each to spend). If that is the case, ring up as two different orders so that you can use the $10 right away.
Also, go to the build a bear web site and sign up for emails and such, you might get some deals through that.