If you want something that you can just go out to the local Lowes, Home Depot, Menards or similar stores the Weber WSM and the Chargriller Outlaw with firebox are both good options.
It just depends on what kind of setup you want to use. While chargriller isnt a top of the line offset Ive used a buddies several times and made some good que with it. Like the above comment states the cheaper cookers have thinner metal and more air leaks which equals more work on your part to keep temp. The Weber from what little experience I have with it hold heat quite well.
Custom 250 gal drum cooker,Weber OTG,Maverick ET-73,Covert Black Thermapen