The K-22s have been climbing in price lately,but it really depends on condition.A set of correct diamond magna grips will add $50-75 and a set of diamond targets would be twice that.To me,the price is too high.
What kind of shape is it in mechanically? Does it just have some blueing wear? Any rust? Bore and chambers shiny? Timing correct? Will they take less? What do you want it for? To shoot or let it languish in a safe to hopefully appreciate and make a profit on it? If it is the latter, it is priced too high, so don't waste your money. If, on the other hand, you want to keep it, shoot the heck out of it, and own something like it that you truly cannot buy new these days, and maybe pass it on to your kids and it is in great shape mechanically it may be worth $500-600 to you. Take a look at what you can buy new these days in its class for that money and see what you find. I save you some time and trouble. Such a gun new doesn't exist.
That's a tad high IMO. The incorrect stocks will take $50-$75 to make right. I would think $600 for one in nice, original condition would be attainable. Offer them $500. The shop probably paid $250 for it...
Assuming it is a good shooter grade k22 and you want a good shoot grade k22, which if you're alive you should, I would offer up $450 and see what happens. 6 bills is a little high but not out of bounds. It sounds to me like a price I would expect for a gun with correct or original grips, but the difference may just be the margin of the haggling.