You need to speak with a Realtor. They can customize the search options to include rent to buy or owner financed properties.
Also can I ask why you need to wait a year before getting a mortgage. What do you need to do to be in a position to buy? I am curious at to your mortgage game plan moving forward.
See my blog at http://bit.ly/findaleaseoption
Bottom line: Some will be listed that way. Most won't. Some will be on the MLS. Most won't.
One piece of advice: Although you would like to buy in a year or two, make the option for as long as possible--say 3 years or longer. The option can (and should) be written to give you the right to purchase at any point during the option. But you want to give yourself as much breathing room as possible in the event that somehow you're not able to qualify to purchase in 2 years.
Hope that helps.