From Hall Spars, you can buy 75% of everything you need to build an a-cat.

Complete mast (assuming with spreaders) $2,780
Carbon Main beam (strikerless) $873
Carbon Rear Beam $512
Fredrickson mainsheet system $269

We're at $4,434. Let's also assume that Ben is going to give me a 10 to 15% OEM discount..at 10% we're at $3991. Let's also say we're going to take a little cost out and go with aluminum beams with strikers; I'm roughly figuring we can drop to about $600-700 (call it $650)for both beams instead of $1385...take off $735 and we're now at $3,256 but still need and still need sails, line, rigging, hull hardware, and trampoline.

Hulls need carbon. I'm not certain about the laminate schedule, but lets say we're using 2 outer layers and 1 inner layer of 5.7oz carbon (standard grade, nothing exotic). It's roughly $45 / yard in a 50inch width (off the street price). The boat is 18' long / so that's 6 yards per hull half for one layer. Three layers is 18 yards per half and there are four hull halves. That's $3240 in carbon...but there's a lot of unused waste and for a 50" width, you might actually be able to get two hull halves out of one width...let's say worst case scenario and with a little bit of a wholesale discount, let's say $2400 in carbon for the hulls. Gelcoat - $80. Core material, $120 for 1/4" end grain balsa. Vacuum bag disposable materials - probably around $150-200 for the hull halves. $2800 for hulls.

We're now at $6056 and need rigging, trampoline, sail, and line. Trampoline (it's been a while since I bought a trampoline) - $350? Rigging, trapeze $100 (synthetic line), dogbones, $30, forestays/sidestays roughly $45 each = $180...call it $200. Sail, $1200. That's another $1880 for a total of $7936. Still need a mast base and pivot hardware...but materials should be under $8500 said and done.

With the lack of materials and lack of hardware (jib, spinnaker, double traps), I'm still a little surprised at the $20k price tag carried by most a-cats when you can buy an F18 that weighs more than twice as much for $14.5k.

That said, I've never built a 'real' people-sized boat before so please take my comments with a grain of salt.

Now, labor...there's obviously going to be a lot there, and we've not even begun to discuss tooling or foils.