The cost of getting into the various courses varies between county boards.
Level I at present is a four-day course, costing £60-90, resulting in a very basic technical assessment and multi-choice paper, before taking a group of 6-8 U11s for a fifteen minute "group coaching" session. Anyone can pass Level I.
There's usually 3/4 run in a county per year on a regional basis(speaking from experience in Devon & Lincs - ie Plymouth/Exeter and Grimsby/Lincoln/Stamford).
It will change drastically very soon - a lot, lot more continuous assessment and practical experience will come in and it will be much harder to pass - I recommened you do one before too long because this will change within the next 6/12 months at the most.
Level II is much more theory based and indepth. It involves more advanced technical models, theory on sports science and a lot of video analysis with an assessed net with County U13/14 juniors. It's a 6-day course and will cost £90-150.
To get involved, contact your local Cricket Development Officer. Going from your profile, it's Tony Bowry, Yorkshire Cricket Board, YCB Office, Yorkshire Cricket Centre, 41 St. Michael's Lane, LEEDS, West Yorkshire, LS6 3BR - Tel (0113) 230 5238