what is a 17.8 width? you mean like 17x8 ? or 18x7?
$750 for wheels is $150 + tax + mounting where you live if buying new. If used, you need to look on CL.
Deep dish will be hard to do because of the high ET, however, you can scrap that and use BRZ wheels which will give you more dish in return for more punishment of your wheel bearings.
This thread is a good starting point - http://legacygt.com/forums/showthrea...ead-11208.html