There are plenty of part-time programs at better schools, and most of them are easier to get into than the regular full-time day programs.
The for-profit schools usually cost more, and I don't think it's worth the investment to go to these schools.
Also, and I'm not sure if this is the case in all the newer schools, but some of them fail out a certain percentage of the class. That's not the case in most schools that I'm aware of. The only school that I visited where they admitted to that was Baylor.
As for the financial aspect, aren't you taking out loans anyway? If you're that worried about paying for it - go to a lower ranked school that gives you a scholarship, or to a state school. U of Houston has a part time program, and the in-state tuition for them is about $15,000 a year. I'm sure there are plenty of other state schools out there with part-time programs.
Bottom line, I wouldn't trust the quality of the newer for-profit schools. I don't think they're worth the investment, and they're certainly not worth the extra stress.
Oh and FWIW, when I visited Denver, they said the part-timers were more competitive than the full time students. That decided it for me! There's no way I'm adding the stress of ultra-competitive classmates to my law school experience if I don't have to.