I've actually done some Google searching and managed to find the following. Not how up-to-date the information is, but this is the charge per bus departure.

Eldon Square - 62.7p
Haymarket - 55p
Gateshead - 47p
Park Lane Interchange - 47p
Four Lane Ends - 26p

That's pretty expensive, to be honest. Consider a bus service like the X66 - there's probably about 700 departures per week? This is just guess work...

700 x 47p - £329
£329 x 52 = £17108 per year