Bob, i use fresh bolts, thanks to getting a massive bulk lot a few years back.
The current price is based on both a lack of time to get work done, and a need to cull non-vintage mowers, basically, i have about 20 mowers i built up at the last place, that i dont have room for, so I'm just trying to get them out the door as second hand mowers, not serviced or restored.
No real work is going into them, a few new spark's, the odd head gasket, but mainly just carby cleaning.
I do the restored thing sometimes to, when I have the time to sit down and give them a good going over, when I do that, they get all new o-rings, spark plug, gasket, muffler, blades, fuel and air filters, fuel line and tap. Then they go for $150 - $170
Other ones are just a basic service, filters, blades, sparky, and seals and gaskets when needed, $120 - $150
$75 is what i charge for essentially cleaning the muck out of the flat bowl, starting her up, and grinding the blades, plus a quick wash, the mower comes out like your average "I no longer need my mower" sale, rather than a reconditioned mower, and when they came to me for next to nothing, and sometimes nothing, and get basically next to nothing spent on them, I get most of the $75 as profit, and the turnover is very fast, I popped up the add the other day, and sold 3 in 2 hours!!
The moment i see the grass ready to spurt, i pull the add, grab a few, and give them a real going over, than the add goes back up at $150 or so, when that spurt hits the lawns a few days later, they come!