I don't know what kind I have, but I just picked one up at Home Depot. They had probably 5-6 to choose from. If I were looking for one now, I would probably look for one of the new ones that can be controlled over the internet (I think Schlage is the commercial I'm thinking of). Of course I have no idea how much those cost! LOL.
I don't remember the one I got being terribly expensive. It's a touchscreen and it allows you to program a full 7 day week. 4 time periods per day (Morning, afternoon, evening and night I believe) and you can set when each time period starts. It has a bunch of other features that I never use as well. I'll try to remember to check the manufacturer when I get home and post it here.
The only thing I'll note is that you want to be sure to mark down a reminder to change the battery regularly. I came home the other day to find the house ridiculously cold (at least compared to where I usually keep the temp so as to keep the electricity bill down). Turned out that the battery was going and the stupid thing had reverted to some default setting. Replaced the battery and all was good.