how old are the underagers? how many of them are there?

I say do a house party kinda thing, order like 2 or 3 honey baked ham's with sides and shit get all your chips, dip, and sodas and maybe a a few pizzas, and goto best buy or circuit city and get a couple $20 gift cards and have somekind of game so they can win that shit....

because you cant even take them to Applebee's or TGI Fridays with $400....once taxes hit, there aint no way you could even cover the 15% tip for the server.

I dunno man...that seems to be the best idea, because that's a tight budget.