I can definitely understand wanting to get away from high rent; however, I would suggest really thinking about waiting until you can qualify for a site built home. Mobile homes tend to depreciate in value very quickly, where site built (in a normal market) hold value or gain value. There are a lot of mobile home owners now who owe far more than they can sell their homes for. Also, the foreclosure rate on mobiles are fairly high right now bringing the values even further down.
I would suggest finding a good mortgage banker or broker (maybe talk to the loan officer at your bank) and ask what you need to do to bring up your credit score. It may take some time, but I think you'll be better off than buying a mobile now. You could also look for a lease with option to buy situation. They are not real common, but you occasionally run into them.
In the mean time, maybe you could locate somewhere with less expensive rent (using your present landlord as a reference).
I hope this helps. Good luck!!!