Znid,
Good luck! I looked at doing this but realized a few things:
1) Building in plywood, a new homebuilt F18 would be roughly $12K, probably more as the cost of raw materials keeps going up ~5-10% year on year. New rig and new sails set you back $8K. For that you can get a nice used tiger and a little more gets you into a Capricorn or Infusion with good quality sails
2) Building takes time. I guesstimated 300 hours, maybe more maybe less. That is time spent training!
3) Designs available likely won't be competitive out of the box. Blade isn't bad but it's low volume compared with the newer designs (Infusion, C2, Phantom etc.). If if the hull shape is fast, getting the rig tuned and the running rigging set properly is a time consuming process. I know, I did the latter this summer, probably spent 60 hours splicing new lines for the Infusion, they turned out well and it was a skill worth learning but it's time consuming!
If you really want to build, go for it! If you really want to sail and are looking to save money, buy a used boat. Good luck.