Patrick,
Plans are probably the cheapest part. I can't imagine building that boat you describe above from the keel up is going to be less than a good $10k, not including motor and at least some basic electronics. As they say, the rigging costs more than the hull!
Also factor in dockage or towing (you'll need to get the driver's license and car now too), insurance, fuel, safety equipment etc etc.
Considering too that you have no experience operating a power boat (larger than maybe a row boat), don't you think buying a used craft you can refurbish is a better way to get started in your nautical career?