I appreciate this is a "how long is a piece of string" question, but I've never had a wheel trued but I've got one that's out quite a bit.
So how much is it likely to cost me to get a wheel trued?
I've got a few good local shops near me - Merlin, Paul Hewitt, Ribble Cycles but I'd prefer to have a general idea of what a fair price is before I bother them.
Thanks in advanced!
If you're close to Merlin, I suggest taking it to them. I believe they have a full-time wheel-builder, so as he's all set up and ready, it should really only take him a minute or two to true your wheel. Especially as he has the best kit available and he must be an absolute master of his trade, as Merlin wheels are excellent. If you take it to an ordinary LBS, it'll be done by somebody who isn't as good at it and only spends 5-10% of his time working on wheels, so it'll take longer.
This is assuming your problem is just loose spokes. If your rim is warped, truing can be quite difficult, juggling the tensions so as to find the best compromise to pull the rim back from its natural untrue position.
I would agree that if you just want the wheel to be rideable and not necessarily perfectly true, you could do that yourself. That's especially if you don't have your brakes set up all that close to the rim. It's much easier with the tyre removed though - put the wheel back, close the brakes, turn the bike upside down to stabilise it, and you could do a reasonable job in 5-10 minutes armed only with a spoke key.