I would think that given the price of the Toolcat, 8-10% would be a good working area given the state of the union. Could be wrong, but most dealers will get at least there if they think you are serious...I'd work them hard either way, you're spending alot of cash on a premium machine. If they hold anywhere near MSRP, I'd walk...You're feet are the best negotiating tool there is.
I looked at them, but didn't want to go to that level of premium. Best of luck.