Al, I've done it both ways (built my own versus bought truss-plant trusses). The one's that I built were for a 30' span (building was 30 x 40). I used 1/2" plywood for the gusset plates, and glued and nailed them on both sides.
From a cost perspective, you can usually buy trusses for not much more than the cost of the materials.
From a time perspective, building your own will add some time to your project. However, for a 14' span you could probably use a single board across the bottom, and they could probably be built fairly quickly. My 30 footers took me three weekends to build, and in retrospect I would purchase pre-made ones today if for no other reason to shorten up the total project timeframe.
If it were me, I'd get prices from a couple of different truss companies, and then compare the material costs with what you can do yourself, and then ask yourself if the time savings is worth it. The last set of trusses that I purchased had a 25% difference between prices between different truss companies. Here in the Raleigh area, Stock Builders Supply had the best deal.
Good luck, and congrats on your progress so far!
Scott
