learning to market my properties

I have two houses on the MLS listed with a realtor. I had them both under contract for like a minute. I was so excited. But then, one of the appraisals came in 30K under askiing price. Apparently this appraiser was too busy to do a goo djob so he took my purchase price, added my estimated rehab costs and stated that was my value for the house. I am thinking he didn't use the same comps that me and my agent used...most likely used short sales and bank owned.

The lender refused to tell me the name of the appraisal company they used. The buyer offered that information to me at the cost of the appraisal (450). So, it's back on the market. I am thinking that I may not use a realtor in my next sale - what do you think????