I recently took the plunge and returned to grad school after several years of just plain working. I'm keeping in my field of practice - social work - so I don't have to deal with that barrier.
I wouldn't worry too much about the changing fields thing. So many people get BS (as in bull sh**, not Bachelor's of Science) degrees in things like basketweaving and then go on to Grad school that it doesn't matter.
Are there no schools close to you? Unless you are trying to Ivy League it, or have a very specific goal in mind in which you'd need a very specific school or program that a school offers, I wouldn't just give up everything. The PhD thing is a different story, but many people commute fairly long distances for that.
I go to Grad School while working full-time (I go part- time, but am Advanced Standing due to my undergrad degree, so I cut out several otherwise required credits) and am able to get by without living on loans. Hence, I can pound it out in two years, vs. the traditional three years part- time. The scary thing about living on loans is that six months after graduation the collection man comes calling, and it's going to be the size of a mortgage payment. Which is great, education typically pays for itself, especially if you have a job that you love getting out of bed for. But don't take out more than you have too!
EDIT: My two cents on psychology. It's a great degree, and I minored in it for my undergrad. Very interesting. But as to usefulness, it's really a state by state thing (billing, etc.). In Michigan we like to say (or I like to say), "Friends don't let friends major in psychology." This is because the job market is so bleak in our state for most people in this field because of licensing thingy-ma-gobs. For billing, they want social work, OT, etc. And in doing a Master's program, you generally have to be pretty dedicated to the idea of going for the PhD following it - which can be very competative and hard to get into. People wait years for internships, etc. So for people interested in Psychology, I like to point out, "Social Work, the other white meat." Not just because I'm a social worker, but because I have MSW co-workers getting head hunted while at work. While the pay isn't big in the field (college educators is another matter), they tend to be more in demand in some areas.