That's true, but often times the 10 G's you put into it will net you a superb TM that actually, in the end, will cost you less than a new underperformer. (Provided, of course, that you actually need a super heat, dual wand unit.)
I have put somewhere around $5000 in mine. I am selling it for $40,000 and it is functioning like new, and is in top condition. You'll pay $40,000 by the time you purchase most single wand slide in units and a van, and still be underpowered.