For some of us building is not an option. Building such a project will take a lot of your spare time for the next couple of years. Spouses and family may not like the idea of you building an airplane and then flying with it.
Also, if you want to fly next week instead of in three or more years from now, there is no other option then to go out there and look for an aircraft to your liking. Remember that when you buy an airplane built by someone else you don't buy the repairman certificate or the experience the original builder has.
There are a number of steps to take before you can shake hands with the seller of your dream machine.
After selecting a couple of airplanes fitting the goals set above it is time to do some research. Get pictures, talk to other owners of the same type. If its clear at this point that its not what you thought of it, just stop. No need to go into the pre-buy inspection phase then. If you do find one interesting enough, get detailed information. Obtain its tail number and call the NTSB or visit their site to see if there were any incidents or accidents with it.
Maintenance records must be kept by the owner including records of servicing, maintenance and inspections and any relevant AD's. Make sure that all logs are present and in good order, it can influence the resale value. Things to check for are:
Get an A&P mechanic (Aircraft and Powerplant Mechanic, or sometimes called a LAME - Licensed Aircraft Maintenance Engineer) and go over the above items with him or her if you are not sure about these topics.
The same friendly mechanic can do the pre-buy inspection, he or she will look over the complete aircraft in detail from tail to spinner. All systems should be checked: fuselage, wings, see if any corrosion exists, landing gear, engine and propeller, fuel tanks, control cables to name a few items. This will make sure that all is in good order and he or she can give you a well informed opinion. With this information you make a sound decision. It's really worth it!
As these are not built to accepted standards (builders use higher standards) it is important to see if any changes are made by the owner/builder that are not in the original design. If any, they must be approved by the kit manufacturer.
Experimental aircraft or homebuilts have a special airworthiness certificate, make sure to check the limitations on it. Get the POH, Pilot Operating Handbook, and read it thoroughly. Verify what the limitations are for this particular airplane.
If you are contemplating an aerobatics capable aircraft have it inspected as if the aircraft was over-stressed (or ground looped), as most aerobatic aircraft will have exceeded red line at least once during their flying career. Make sure to check for any STCs or modification that would render the aircraft unsuitable for this purpose.
Make sure that all documentation is complete and in good order; including airframe, engine and propeller log books, airworthiness certificate, operating limitations, aircraft data plate, weight and balance forms and all current maintenance records. It is very strongly suggested that you have an A&P mechanic or someone very familiar with the type for inspection on hand. With all your research and inspections done together with your A&P mechanic, it is time to make a decision whether or not to buy the aircraft or to go on to the next on your list. Good luck!