Westside222 is a wise person - i agree.
I applied to seven schools last year, and after paying the initial fees, the secondary app. fees and then paying to go to the interviews i did attend - well, the cost is staggering, really (explains why "the rich stay rich" lol)
You don't want to limit yourself too much, but don't apply to schools you'd turn down in a second for anything else - that's a waste of your time, effort and finances
I would suggest picking out your top schools and trying to focus on them - easier if you manage to get early interviews (well, before dec. 1) That way, in an ideal world, you could get into a school for sure, cancel other interviews, and then still pursue any schools you prefered over the one you'd already been accepted at.
The DAT prep book i used suggested applying to 7 schools - i think i was just really lucky in having 7 be overkill last year.
GOOD LUCK!