Lowest price for KM2s is usually Costco. You have to special order them. They will mount and balance to your wheels for carry-out. For liability reasons, they will not install them on your rig.
Lowest price for MTRs w/Kevlar, discounttiredirect.com. There is currently an $80 rebate on 4.
Tires for 17" wheels are usually load range E tires (10 ply) that are heavier and designed for lifted 1 ton crew cab trucks with huge towing capacities. Some are load range D tires (8 ply), but they are still very heavy and designed for heavy trucks. This is part of the reason for the higher expense.
If you want a tire in a 17" wheel, the 35x12.50R17 Goodyear MTR was designed to run on lighter vehicles like JKs. They come in a load range C and are $288 each shipped on discounttiredirect.com, plus the $80 rebate on 4.
If you want to run a 15" wheel and not have to worry about clearance or grinding the front calipers (which is no big deal), you can simply order a wheel with 3.75" backspacing.
The 35x12.50R15 MTR w/Kevlar is $216 shipped, plus the $80 rebate on 4:
You may be able to find a local tire dealer that will price match discounttiredirect.com, plus charge $10-$15 per tire for mount and balance, plus add a charge if you want road hazard warranty coverage.
As mentioned above, you may be able to get a great deal on 35s from someone upgrading to 37s. I sold my 35" Toyos for a great deal to a friend when I upgraded to 37s.