I was thinking of upgrading from my 2013 iMac to a 2017. Problem is that the i7 3.6ghz version is way more expensive than the i5 3ghz/3.4ghz models. So I was thinking of upgrading the processor from the 3.0/3.4 to the i7 3.6 while I was in there upgrading the ram. Looks like on eBay I can get the i7 3.6ghz processor for $70ish. thoughts?