I just thought I'd jump in here...
Under no circumstances should you consult with a realtor. They are NOT there to cover your butt! They know zippo about building codes, etc. Do yourself a favor and hire your own building inspector. I recommend you take a look at the web site for The Independant Home Inspectors of North America (IHINA). Their web site is www.independentinspectors.org
For anyone in need of a home inspector on a house purchase, do yourself a favor - the last guy you want inspecting your home is the inspector you r.e. agent refers.
If you were buying a used car and the seller were to say, "Here's the name of my mechanic, have him look the car over for you.", would you? Use the same logic when buying a home - the realtor only gets paid if the sale goes through.
As for building your own home - Congrats!!
If you're really brave, you can be your own contractor. You can get a book at Home Depot (and probably lot's of book stores) that will tell you how to go about it. I've never done it myself, though.
I hope this helps....