If it's only for occasional use, I picked up one of the cheapy chinese ones from Crytec for a little over £50, new and with warranty, and was pleasantly surprised by how good it is for the cost.
Yes it's plasticky, a bit vibey and a bit heavy for the size of it, but it's been a grand little thing and cost less than a bar and chain for a 'proper' one.
I shoved an old sugihara bar and chain on mine off my little echo, as the standard chain's a bit soft.
If you do end up going stihl/husky/echo etc, a used husky 540 can be a bit of a gamble as once they stary playing up, they soon get prohibitively expensive to fix.
The 36cc echo's a bit of an oddball too, just feels all wrong ergonomically, but runs well enough.
