It's a shame that some people (and I don't just think it's young people) don't have more sense.
I really don't think you should be offering more though Andy. If they don't see or appreciate your offer then they aren't the right candidate. There are plenty more young people desperate for work.
To add to some later posts; I am a trainee and I started by buying my own PPE and CS30/31 tickets then I harassed companies until I got an interview (It seems impossible to get a tree surgeon to remember to call you back). I started working for £50 a day for an 8ish hour day and I thought that was fair. I also started doing jobs for family and friends to gain experience.
If they've got tickets £50 a day for a trial period and £65 a day thereafter until you deem they are worth more. If they haven't got tickets put them on a day release college course and pay them apprenticeship wage (£4 an hour or something) it goes up to minimum wage after a year and you will be able to guide their learning from the start. If their not happy with that then they probably aren't committed to the job so much as the pay check. But everyone has different circumstances, and at the end of the day you've got to think, not 'What is an apprentice worth, what should I pay...' but rather "What is that apprentice worth to me?" Then talk to them and work it out. Because you don't want a young person desperate for work to just take the first job that comes along when they aren't really happy with the circumstances and then be looking to move straight away, or worse as soon as you've paid for their tickets!
Currently working with a company who I am on a trial period with and they asked me to invoice them. I don't know what the other lads get paid or what other people in my position would charge. I have several tickets but not a huge amount of experience. In previous jobs (in different industries) my standard rate has been £100 a day, but if I really respected the fact that the company trusted me to value myself and so I invoiced them at £60 a day and I think that £300 a week should be sufficient for anyone with minimal commitments i.e. young people and apprentices