Here's the skinny, or the best that i can make it.
Trips are camping based. Costs above are Mark's expences to come and coach you (v cheap - the expences, not mark).
In addition you are likely to need to pay (1) camping charges, (2) perhaps some transport costs if you lot share or hire vehicles, (3) your food, (4) all those shiny kayaking items that you see in the shops you visit on the way home[1], (5) beers etc for the coaches helping - you might want to buy them dinner cos they is ace.
Dan
[1] our tally was 1 wet suit, 1 boyancy aid, one skull cap, 4 bungs, a magazine and various other sundries. We almost bought 2 helments and new feet.