Hi Joanne,
I don't know the full breakdown, I'm sure it is on the site somewhere but I can tell you roughly what it costs/has cost me to be a practitioner if that helps:
First Year (including training, buying books, DVDs, CDs for class, advertising - leaflets, website, insurance): around £3000
Subsequent years (including CPD, buying parent materials, advertising, insurance and room hire): around £2000
I'm certainly not rich by any respect and would imagine I would earn a great deal more if I worked on the checkouts in Tescos and I'm fortunate that we don't rely on my earnings, it just gives us a bit of pocket money.
For me, however, I don't do this for money (I can't imagine many practitioners do), I do it because I've had two bad birth experiences that left me feeling terrible and then I've had two wonderful, empowering births using HypnoBirthing. I want to help other women feel like I did with my last two and for every email that I receive that says "dear Sarah, thank you so much, the birth was wonderful" that's worth more than any amount of money, so so long as I can help women feel like that and so long as I make more than what's going out I'm happy

Having previously worked in a soul destroying (but highly paid) job it doesn't compare to the job satisfaction you receive as a HypnoBirthing practitioner! so I'd say go for it if you can!
Sarahx