I have used the local college hairdressing academy and they do all sorts of hair dressing. They definitely do highlights and they are very cheap. I think that the hair cut if done by a Level 3 is £7 and by a level 2 was £3! They are checked by the tutor before they do anything.
I have also used their beauty salon and am very impressed by the service. 1 hr luxury facial last week for £11.
What is your natural colour? I am naturaly dark blonde and now only have my highlights done once a year when it goes really dull in the winter. Would that work for you? Having said that if you do want to DIY dark I agree that there are some great ones on the market at the moment.I used an academy for my highlights once. It took 6 hours! Great cut but I was soooo bored! I then started going to granny salon in the village which was even cheaper and I emerged within the hour with neither a purple mullet or blue rinse!