Have you actually met with a lender yet to evaluate your situation? I suggest starting by going to a local bank and speaking with them. They will have a different perspective then any credit repair company and can tell you what needs to happen in order for you to qualify.
"Rent to Own"- unfortunately doesn't really exist in Real Estate. There is "lease with an option to buy" where you pay $5,000- $10,000 (agreed upon amount) non refundable fee to reserve the right to buy that particular home at a set price for a set time frame. If you don't qualify for a home loan or fail to use the option you do not get your money back... And the monthly rents you've paid does not usually go toward the purchase price; it's just rent.
There's also, "owner carry"- which is when the owner owns their home free & clear; you sign loan docs thru them and make the monthly payments for a certain amount of time; then again, you try to refinance or miss a payment and they can repossess the home from you.
Many owners don't like this because it doesn't help their cash flow at all but sometimes we get lucky.
So, meet with a lender first and then we can determine which route to pursue.
I am sorry about your situation with your landlords. Unfortunately, I think you are asking if you can buy with low credit scores, and unfortunately not. Lenders will require a 620-640 minimum. If you need help improving your credit scores I have free tips on my blogs here on Trulia or you can call my office as we guarantee to improve your credit scores so you can qualify for a mortgage.
Best of Luck;
CEO & SR Credit Repair Specialist at
Everlasting Credit Repair
Ex-Mortgage Banker of 10 years