www.troybilt.com/webapp/wcs/stores/servlet/product_10001_14102_89548_54965_-1MSRP is $1200, so he likely paid $800-1100 depending on the time of year he bought it.
My local salesman estimated a very similar model would have a 5yr lifetime before major repairs required with my 2 acre lawn. So that is about a $200/yr depreciation if his lawn is similar in size.
The grass catcher is worthless to you if you won't use it or don't want it. It's actually beneficial to a lawn to distribute the clippings over it. Some folks just want the golf course look, then wonder why they're having to fertilize their lawn yearly or more often.
That said, I don't think his price is far out of line, but a little high ($75-100) if his lawn is more than an acre.
ETA: The estimate I came to assumed that the engine was properly broken in (break-in oil) and was properly maintained with at least one oil change and air filter replacement per year. If it wasn't maintained impeccably, the estimate decreases exponentially. At two years, it may be ready for a set of belly belts also @ $150 or so done by a dealer. $30-50 if done by yourself. I run the belly belts till they break, though.