What's your budget on the high end? And how fast do you want to buy the next roaster?
budget... hmmm. nothing explicit, I guess its flexible. No way would I pay more than 10k, would strongly prefer under 5k. I've come to terms with the fact that my coffee addiction is for life and am doing the "its only pennies a day" mental gymnastics.
Especially since I figure I pay around $5 a pound or so for green coffee, and would easily pay $15 for someone else to roast it. So that's a $500 a year payback for my use alone, assuming a pound a week (I might drink more than that. Yes, addiction... ). So analytically 5k = 10% ROI (superficial math, I spend enough time on coffee without doing time value analyses... )
And that leaves out that I have a very specific flavor profile I tend to aim for in my coffee, which is hard to get from other people's roasts... ie I really want a east African fruit bomb mixed with stubbies Brazil beans, roasted into the start of second crack...
So as long as the roaster will last 10-20 years with reasonable maintenance, I'm happy. That's something that annoyed me about the Hottop. I used it no more than daily, usually every couple of days, and it still only lasted 4-5 years, and has been marginal to this point. I've repaired it more than once.
My guess is a commercial sample roaster in home use will be more like a commercial espresso machine - ie effectively unlimited.
Please correct me if I'm wrong..