if you want one that has multiple probes so you can monitor smoker and meat temp simultaneously (highly recommended), you basically have two choices:
1) Maverick
2) Nu-Temp
I have the Maverick. You can get it for about $40 on gadgetsource.com. I've never had a problem with mine. Other folks like theirs, but they aren't getting the range they had hoped.
The Nu-Temp is about $70, but is expandable to up to 3 probes. Someone correct me if I'm wrong, but I believe it only comes with one to start with. The others can be bought for $10. To expand to three probes, you need to buy another probe and sensor, which will be another $30.
I think the general feeling is that Nu-Temps are probably a higher-end product (though some folks have range issues with them as well), but you pay about twice as much (or more) to get up to three probes.
So, if you are cost conscious, then Maverick is the way to go. Hard to beat - on price and function, in my opinion.