If I remember right there's a small campsite at the top of the hill in Tobermory, I wouldn't fancy it on foot it looked a fair old walk. The SYHA right on the harbour is nice and cheap but gets busy, brilliant handy for the pubs and chip van though. There's a free campsite in Calgary Bay, a bit of the machair set aside by the council for tents with a small toilet block and a bus stop. Lovely location, there's an old pier on the north side of the bay as well though I don't know what state it's in, I've only ever come in from the land side. There's another campsite down from the ferry slip in Fishnish, I thought it was a bit naff, all prim and proper, even astro turf over the tent pitches.