Browse eBay and keep an eye on threads dedicated to selling Pro licenses on this forum. I was able to snag an A6 Pro for $300 on Ebay (advertised on here) and upgraded to A7 Pro for $299 which was a few hundred in savings. Make sure the person you are buying the license from is the ORIGINAL owner. A license can only be transfered once.

My User Contributions master list - my initial post links are down but scroll down page to find list to active links