Tri Tip not all Brinkmanns are bad LOL.....
Actually the price of a brand new one would be $10 cheaper.... Brinkmann Smoke 'N Grill
I have 2 Brinkmann Smokers, but I am with Mike, and Toby on this one, that is a piece of junk and you will be spending more time and money on trying to figure out how to get it to keep its temp, or something else than it is worth.
Since you need to stay portable, have you considered using a regular Weber kettle charcoal grill for smoking???? I use mine like this all the time. All you do is set it up for indirect heat, and add wood chips to it... Easy to do but yet it is effective. This way you can stay portable, get the smoke you want, but not have to shell out alot of money, especially if you don't have it. It is not full on smoking but gives somewhat of the same effect. Just another route you can go until you can get a proper smoker.