Could be that the seller ended up with a defective unit, has done the repairs, but simply doesn't trust it to be reliable now...or found he doesn't like that particular smoker design after actually using it. It's a judgement call, no matter how you slice it...go with your gut and you'll decide what's best for you. I think I would have backed away, as well.
I have the maze and the tube from Todd...they do work well as long as you provide what they need to function properly...sometimes this means making some minor mods or additions, but generally it's nothing serious.
I resided myself to using propane smokers (I do smoke on my Weber kettles, as well), being a good compromise for temp ranges and an acceptable ability to control temps. My SV-24 will run all the way down to a barely visible flame for warm smoke (lower the cast iron smoke tray closer to burner), all the way up to nearly 400* over ambient temp. It pretty much can do everything but a true cold smoke, unless I toss in a pellet smoke generator, and then it's game on. I prefer propane over charcoal for long, hot smokes simply because I have not mastered a variant of the Minion Method (yet) for my current charcoal rigs, and I detect that coal smoke taste in the food at times when using the minion with briquettes...not what I want out of my smoked food (lump may be more pleasant, though I find it more challenging to control heat). Propane will have some temp swings, being there is no thermostat (there's a learning curve to set the temp and get it close), but it takes pretty severe changes in ambient conditions to really throw them off of your target temp by any significant amount. Best part for me is that propane is portable just like charcoal, so I can take it with me anywhere I want to go (some areas have bans on solid fuel-fired cookers, especially during drought conditions)...and I do travel with my cookers, across town and out of state. A small and quite inverter generator can easily power an electric cooker when off the grid (they sip fuel when operating under light loads), but they come at a price, and have to be maintained (I have one of them, as well). Overall, propane is my go to for smokers...but I do prefer charcoal for grilling and for shorter smokes (very even heat and excellent temp/grease-fire control with the kettles). Just some food for thought.
Good luck in your quest!!!