How was the market valuation done on Eric's house when he sold it to you? 
 Something like 10 comps in the area, plus had an appraiser come in.  I know Eric got fair market value, I live 2 doors down from him(in the exact same model)and did a refi just a couple of months before his and was appraised about the same as his.(mine has more upgrades yet came in a smidge lower) 
 FWIW, with the upgrades on my house(again same model as Eric's) my house is worth 340K.  I know this because I am adding a pool and going to refi again.*
* Edit  I didn't mean this to sound like pride.  I am trying to demonstrate that the market has indeed gone mad.  We paid $165,000.00 in 2001 and the house has more than doubled since then.