"if you're paying 50 quid a month for 10 simultaneous streams, how is a radio station meant to pay for itself when it only has ten listeners?" aye, it can't.. Those are 'hobby' broadcaster rates offered by a third-party company. The only chance of making a profit is by increasing the numbers of listeners and negotiating a volume licence with the licencing companies yourself. If you find out the agreement that the site your working with has got, I'm v interested to find out more.
Nowadays people have more music than they can listen to! Ah well.