Outrageous overbill by Kanter Automotive

Some time ago I posted a request searching for a 65 Barracuda power steering pump. Unfortuantely, because of the low core value, rebuild cores have been unavailable. Kanter Automotive in Boontown, NJ, said they could sent my pump for rebuild. Having done business with them before, and not knowing the industry, I trusted them to deal with a relaible rebuilder.
The rebuilder sent returned the rebuild pump directly to me, with the invoice.
The invoice, including shipping, was for $146.44. Kanter billed me for $340.75. I spoke directly to Fred Kanter who told me a $194.32 markup was a usual business practice. I expected some markup for their labor and overhead , but not 132%.
I'm warning anyone who will deal with Kanter to do his homework before agreeing to buy.
As an aside, Kanter told me I should not have been sent the invoice. An educated consumer is apparently not their best customer.