Masterbuilt 40" electric smoker right at $400.00. The 30" one is around the $300.00 point range you speak about. I love this thing! You have to add chips periodically through the smoking process especially if it's a beef brisket or something that is in there for 8 hours or so. It's not a big deal though and simple to do.
This smoker is my second smoker. I had a charcoal smoker in the past and it worked okay but the electric one is much more consistent with temperatures and such. It has a light inside and the 40" model has 7 meat shelves. In the 3 years that I have owned it not many weeks have gone by where I did not use it at least once each week. Sometimes I might use it 3 times!
I'm no expert but I like the electric smoker as it's simple to operate and the temperature is really consistent. You can do so many things with it too. Here are some of the items I have smoked.
Jerky - man it tasted good and was a lot of fun to make. Set the temperature at 165-170 and smoke until it's at the dryness level that you want. I can check the smoker with my phone and raise of lower the temperature with my phone if I want to or need to. I can also check the internal temperature of say a beef brisket or roast from my phone also without going outside to look at the control panel. Pretty slick.
Pork roast, pork belly, pork ribs, beef ribs, beef roast, beef brisket (doing another one next weekend), ham, whole chicken, fryer chicken (cut up), salmon, macaroni & cheese, baked potatoes (Do in the oven until almost done and then poke holes in the potato for smoke to get inside and put in the smoker with the meat you are doing for the last hour or so.), rib-eye steak (Smoke for 30 minutes and then put on the gas grill to finish and sear the outside. I guess it's called reverse searing. Oh man is it good.) I need to get a turkey and smoke it. Haven't done that in the electric smoker yet but have done several on the old charcoal one I had.
You can do a lot with the 30" Masterbuilt smoker but If you can swing it the extra size of the 40" is really nice if you want to do a larger batch of meat for some occasion. You can put a lot of jerky in the 40" smoker so you don't have to do so many batches if you are making a lot at one time. We had several people coming over for dinner one day and I had 6 racks of pork ribs from Costco on their and two cut up fryer chickens all at once. It turned out great.