Another very good option in your price range is the Char-Griller Akorn Kamado grill/smoker. Basically a poor man's Big Green Egg. For only $299 or so, you get about 95% of the performance of the Big Green Egg at less than 1/4th the cost. I have owned a few different smokers in the past and this one produces a much better final product with much less effort and much less fuel.
This grill/smoker seals up so well that charcoal usage is very low. Additionally, the sealed design has much less airflow than other smokers, the meat retains moisture. I have smoked pork roasts, beef roasts, turkey breasts, hams, and pork loins over the past month. No injections, no brining - just slapped a rub on the outside of the meat and put it on the smoker. BEST TASTING MEATS I have ever produced on a smoker. My wife claims it might be some of the best tasting meat she has ever tasted anywhere! Juicy, tasty meat every time!
The added bonus is that I can easily grill and sear steak all the way up to 1,000 degrees F with no problems! It makes fantastic pizza at 700 degrees!
(In the past I have used an el cheapo vertical box propane smoker and also a horizontal side firebox stick burner.)