As you describe it, 30% below retail price after taxes I think would be fair.
There are recondtioned Festools sold by Festool authorized retailers that already go for 10-15% off, that come with the 30 day return, and 1 year warranty. You're not a retailer, so you can't expect someone to pay the same.
If you were selling another brand, I wouldn't expect as much, but Festool is quality stuff.