On the cost thing, you will need:
wetsuits
boutancy aids
gloves
blocks, blocks and more blocks
cleats
dyneema rope
trailer services
repairs to older boats – inc wood work, epoxy fillers, varnish, and more varnish
Old boats, especially wood will leak and they will get rot, they are heavy to lift out the water after a day sail and a bit of an effort to put away, newer designs are loads more user firendly in terms of taking on water after capsizes, something like an rs200 or 400 however they arent cheap and they will need less maintenance.
Check out people like trident sailing, purple marine, mailspeed marine.
Dont let me put you off though! Its a wicked sport.
Just sorting out details of the Round the Island race Ive entered, 1800 boat start! Get in!