those little washers shouldn't be to expensive to buy, the most expensive would be the replacement camcover gaskets themselves, and you local Toyota dealer should have them on the shelf
and just to give you and idea i paid $1.45 per washer, so it ended up being $11.60 for all 8 :wink:
and being that your from england, it will depend, just give a few toyota dealers a ring and get a price.