Your mortgage depends on your qualifications and has nothing to do with how the home is presently financed. You may wish to check with me to see if the location allows you to obtain a USDA mortgage or, if you're a veteran, what a VA loan would entail as both have lower down payments than FHA.
Eagle Nationwide Mortgage Co., a subsidiary of Eagle National Bank
Simply because the seller has an FHA mortgage on the home your looking to purchase doesn't prevent you from obtaining a FHA mortgage yourself. So long as you qualify, FHA financing is the best way to go!
If you are thinking of buying, you should meet with a lender soon to get pre-qualified and have all your questions answered. Perhaps you could try Steve, he is right on about these upcoming changes. The FHA program will be experiencing adjustments, such as a reduction in allowable seller contributions from 6% to 3% of the purchase price.