16GB of DDR3 should go for ~$70 on eBay, the 2500 should fetch ~$50, and a 1500X, 16GB of DDR4 3000MHz, and a B350 board should be about $440 including tax. I personally wouldn't buy an old z77 or z67 board for $100 when you can get a new b350 for the same price, this seems like a good reason and time to upgrade.