I did ROP dental assisting to see if I really wanted to be in the field, and the internship that they make you do as part of the class was one of the best experiences of my life, since I was able to work for like 6 months at a no/low income children's clinic in Buena Park. If anything, this really impressed the admissions committees, and showed them that I was really dedicated. Also, just about every dental school requires that you do job shadowing, this internship covered that and beyond for me.
As far as the SAT, I'm pretty sure you can apply for a fee waiver? And I also don't think that thing about the SAT's is true - you should lookt it up for yourself, just go to the website and fill out an application, it takes like 20 minutes.
Also, the only way 99.9% of people go to dental school is with loans - EVERYONE gets loans. It is way too expensive to pay out of pocket, even if you're upper middle class or whatever. I'm just going with the assumption that I'll be about a third of a million in debt by the time I finish, since it's about $75k a year.
If you really really need to, look into other student loans for your undergraduate education, as they'll merely be a few drops in the bucket compared to the rest of dental school - especially if you go to a Community college (Go Go Cypress College Chargers!
) , and then a cheaper university like a CSU or a UC (Go Go Anteaters!).
It sounds like you're in CA, and if you're over 16 I'd take the CHSPE if you don't have your high school diploma already, and then maybe do the dental assisting over the summer (it's only like a 2-3 month class). Oh, you should check if your ROP combines it with Dental Radiography, some do, but the one I took mine at had it as a different class so I took both at the same time. Also, DO NOT do RDA, you don't need to. RDA is more for people who want to make that a career, just like an RN. If you want to do dental, just do the CDA (certified dental assistant - which the ROP classes are), and then move on. RDA takes atleast 2 years sometimes.
One way or another, it sounds like you've got a really interesting and compelling story, and that matters a lot for dental admissions, and believe it or not, gives you a better chance for admissions.
Good luck, keep on keeping on, and if you want to be a dentist badly enough, you'll be one eventually - the money factor won't stand in your way. Let me know if you have any other questions.