dont pay him.. sack him and get a new apprentice!!! cheaper...
lol
seriously the way i look at pay and stuff is HOW MUCH WOULD YOU LIKE TO BE OFFERED if your in his position!! keep in mind is he a good asset and will he stay with company long term / do you want him to stick around??
best person to ask is the spark in question, find out how much he would like or even better NEEDS to be able to live on! (serious note) and take that in to consideration, i find that if you pay is above average for his skills he will stay happy and produce better results.
pay him peanuts and unfortunately only monkeys turn up for them...!!