There are a number of websites for people who seek a lease to own deal. I don't know which sites are best, but you can google "lease to own" or "rent to own." You also can check with real estate agents in your area, especially those that handle rentals.
@Home Properties and Management
There are very good prices in Arizona right now. Lease with optioins to buy are not as plentiful. Although there were no lease option to buy within your $900/mo price range in zip code 85339 (Laveen) there are some in other areas of the Phoenix metro area at $900/mo or less. To see these lease option homes: http://www.flexmls.com/link.html?u89kfw8do5i,12,1
If I can answer any more questions for you feel free to contact me directly.
Jeff Masich, Realtor
Arizona Homes and Land