Worth it to apply if I can't attend without merit aid, given limited # of schools I can apply to?

Have you checked out the following site?:
http://automaticfulltuition.yolasite.com/

Are your stats high enough to qualify for any of the listed automatic full tuition / full ride scholarships?
If so, do any of them appeal to you?

If you qualify for an adequate amount of merit aid at any of these colleges, then one or two of them can be your safety schools. Once you’ve identified an admission and financial safety you’d be happy to attend, you can afford to take a little more risk on your match and reach applications.

If you are a low income student with stats high enough for a guaranteed full tuition / full ride scholarship, then you may also have a shot at one of the colleges that claim to cover 100% of demonstrated financial need:
http://www.usnews.com/education/best-colleges/paying-for-college/articles/2014/09/15/colleges-and-universities-that-claim-to-meet-full-financial-need

Try running the online net price calculators on some of the less selective schools on this list (e.g. Holy Cross or Trinity), if they have the programs you want.