Build new or buy used?

I am considering building an Elco 26 from a Weston Farmer plan. I have cabinet making skills but have never built a boat before. I can see my first problem will be coming up with a structure to build in. Beyond that, I am sold on cold molded hulls for strength, weight and durability features and would want to incorporate this into the boat. My problem is the 3-5 years I imagine it would take to finish the project. This is where my question lies: Is it practical to buy a used boat and convert the hull to a cold molded variety, or if I had it done at a shop, would it cost well beyond the value of the boat when it was finished? If I did get a used boat(Under 30') I feel I could easily repair or redo the topside, motor, etc.. but the facilities needed to do the hull would put it out of reach for a home job. Thanks in advance