Met with a Seller Today

I was driving down a street and noticed that there was a FSBO sign out. I immediately called it and set an appointment for Monday at 6pm. The property was built in 2004 and the seller never actually finished the house. They are asking (at the time of this writing) $550K for the property. I know I havent completed my first deal yet but they are asking full price for an unfinished house! I set the appointment but before going to it I tried to pull comps for the property, there werent really any so I went by what the appraisal said (not a good choice but I figured it was ballpark). Since it is an unfinished house I estimated that it needed about $125k of work since it is a 4k sqft house. When I presented my offer to the seller he seemed furious, I offered $230k (to start negotiating) but he got mad and wanted to leave. The whole time I'm asking myself why didnt I do more research or why was he not open to negotiate the price up. I know this is part of the process but I felt and I'm still feeling a bit down about it. But at least I met with a seller right? Let's see how my next adventure goes...