Harriet Kelsall's reply:
This varies enormously depending on the type of shop, the location and how much they have to 'do'. For example a nationally famous department store specialising in designer work in London will have high rates and expect to mark things up about x2.5 area and sometimes even x3. However, some much smaller craft shops only expect to mark something up x1.5. I'd say the 'norm' is about x2 to x2.25 but it really does vary a lot. The bigger and more 'expensive' their set up, the more mark-up they will need to take to pay for it all. So what I mean here is that if we assume they will price x2, they sell for you at £50 and then you get £25. This sounds awful when you are starting out but if you have more visibility of shop rents, rates, staff costs, fuel costs, insurance costs, it begins to make more sense.
So the best thing to do is to have a converation with them and ask them what they expect their margin multiple would normally be. They will normally be honest and helpful with this.
You also have to ensure that you cover your costs and 'wages' too. So it is a good idea to work this both ways round. First think about how much you think a cusotmer would realistically pay and then divide it into 2 or whatever margin is appropirate and see if you think that amount pays for your mateirals and importatnly your time in designing and making and also in everything to do with setting up your business.
For example if you want to charge, say, £15 per hour and the piece takes you 2 hours, then you need to charge £30 for your time, plus materials plus a bit more for the time that you have to spend in your business doing things other than make that one piece. So you probably need to charge something like £40 for that piece which means if you are selling to a gallery the retail price might end up needing to be something like £80 or even more if they are also VAT registerred and have to put 20% VAT on top of that.
There are a few craft co-operative groups, not-for-profit groups who charge much less of a mark-up to sell your stuff but these are few and far between. Many designers try to retail directly to the public for this reason but then you have a lot of other expensive challenges to overcome.
You will find your right path I am sure - it all seems a bit odd at first but you soon get used to it and find a way.
I hope this helps and good luck,