How much discount typically for a new MC275 to expect from a dealer?

I can't tell you the name of the dealer here. They have always given me 10% and no sales tax because the state they are in is tax free. If you buy 2 pieces, you will get 15% on the second one.

 It’s the way you work it. I’ve always received 20% off of McIntosh gear from my dealer. I also don't pay sales tax if I pay cash. The deals are there and don’t let them tell you otherwise. I won’t buy any new audio with less than a 20% discount, as if I want to sell I’m not taking a major hit. As others mentioned if you can get the demo model it’s much easier to get a discount as well. I recently purchased a pair of speakers and had to take the floor model to get the price I wanted. But with original boxes, pristine condition and already broken it was a better deal than new. 
 

McIntosh offers a 3 yr warranty for new equipment.   I am sure you can find a used but mint amplifier that is less than 3yrs old- and probably less than a 1 yr old- for 25% less than msrp.    Buy used, still have a warranty.  Best of both worlds.    Most problems manifest in the first few months of use.   

Best Buy carries McIntosh in some of their Magnolia stores. They offered me 10% off one will no struggle at all. 

If you're worried about price, why don't you just buy a Bob Latino M125 monoblock (120 watts each) pair for more than $1500 less than it would cost you for the Mac?   And you can save another $700 or so if you buy it in kit form and build it yourself.  You can't begin to get that kind of satisfaction from buying any commercial product.

http://www.tubes4hifi.com/bob.htm#M125