What is a fair price to pay for a Late 2011 17 in.

I'm looking to upgrade from my current late 2010 13 in MacBook Pro, which has the last of the core due 2's. I find that I'd like some more speed and increased screen size. I've looked at the new line up and simply cannot affored the new 15 in. So I started looking into the last edition 17 in. models. I found some in the 1300-1500 dollar range. I have been looking at models with i7 2.66 Ghz processor, with around 8 GB ram, and a AMD Radeon HD 6770M. I would most likely upgrade the ram to 16 GB and throw in a SSD. I'm aso interested in getting the high res matte display. I would also take a 15 in. with similar specs. My question is as to what is a fair price to pay for a model like this? I also want to know how many years are left for a computer like this before it is completely outdated? Thanks for any and all help.