What have they quoted you Dorian? Send me a PM if you like, I'm a Mortgage Broker (if you need that sorting I'm more than happy to do it ).
We deal with Conveyancers all the time, what I'd say is that you very much get what you pay for - if they're cheap the are for a reason, either they're very busy and you don't always get a great service or they're not very good. A decent Conveyancer can sometimes be the difference between a sale happening or not, all in my opinion obviously.
Got to concur with most of what's said, D. It's the usual story - you get what you pay for. The cheapest EA will probably be desperate for work and may not pay to market your property in the best places and Andy's spot on when he says a decent solicitor (preferably with a relationship with the EA) can keep the all too fragile conveyancng process in one piece.
EA's rates will vary from city to city so there's no hard and fast rule to what percentage you should pay. Any decent one will know wat his competitors charge and won't undercut by much. Make sure you know how they are going to market the property - someone mentioned Rightmove and Vebra - they should preferably be on both (the internet is essential these days - especially at the top end ) and ensure they are well represented in the local (quality) press.
There's tons of sharks out there so go with a member of the NAEA as you've got some redress if your not happy and they ensure there is a certain level of quality.
You didn't put Ruff wheels on your Zed (sorry Tim ) so don't sell yourself short to save a few bob.
Hope that helps, D. Good luck.
PS Maybe we can all have a man's beer when you get up north.