I can't think of anything more disadvantageous to buyers than a rent-to-own scenario. If nothing else, there are few if any available properties (owners would rather cash out than hold on to the homes for any length of time) and most need considerable work ... there's a reason why they can't be sold in a traditional manner. Realtors in Texas are not permitted to participate in rent-to-own transactions (thus, no MLS listings). An attorney is required, along with two distinct contracts ... one for the lease, the other for the sale. You'd have to qualify for a mortgage at some time (generally at the end of the lease), and only a small portion of the rent (if any) would be applied toward the down payment, requiring you to come up with a significant amount of cash. There are numerous discussions about rent-to-own purchases on Trulia and other such sites. Please take the time to read the forums ... you'll get a better idea as to why they're such bad a deal for consumers.
A relatively small number of properties are available on an owner-financed basis. However, you'd need at least 20%-25% down, the interest rate would be considerably higher, and you'd have to qualify for a mortgage to pay off the owner (this is known as a "balloon"), generally in three to five years. Once again, it's not a viable option for most people. Both of these transactions are incredible opportunities ... for the owners.
Few if any sellers will accept a contract for purchase with a contingency provision (i.e. having to sell another property prior to buying the new one). My recommendation is that you lease a nice home .. most landlords require a year's commitment. During that time, focus on selling your current property ... you'll likely have a significant down payment, and your options won't be as limited.
If I may be of further service, please feel free to contact me. We (my wife/partner and I) enjoy working with new Houstonians (currently helping two families settle in ... one is from Dubai). There being no cost to you as a tenant or buyer, taking advantage of our expertise can only be of benefit during your location. I look forward to hearing from you.