I think that starting bid is realistic FOR A MECHANIC that knows Commandos.
I also think it MIGHT end up over $8,500, maybe even closer to $10K...
Parts & materials
Tires & tubes $400
Carb cleaning $20
Oil change w/ filter $60
Front brake cleanup & new hose $150
Rear brake cleanup & new hose $150
Battery $80
That's under a grand, easily, for typical aftermarket stuff. (Higher for higher quality stuff)
Labor
Tire swap- 4 hrs. (less, if you have a tire machine)
Carb cleaning - 2 hrs.
Oil change - 2 hrs.
Front brake overhaul - 4 hrs.
Rear brake overhaul - 5 hrs.
Battery swap 1/2 hr.
That's less than 18 hours, so an easy weekend's work.
If you have to have a shop do the work, you'd be looking at anywhere from $2K to $3K depending on "local shop" or big-box dealership shop.
Starting bid, do the work yourself - $7,500 Not bad at all, if you ask me.
Good title and very nearly original bike...