That's what I've always heard too, and what makes best sense to me. After seeing what the market will bear, of course.
And it depends a whole lot on what you pay for your materials. AND how and where you sell your work. If I get my materials and the high LBS (local bead store) price, and sell wholesale, I don't mark up that component. If I buy wholesale or better and sell retail, that part might be 6 times the cost of the materials.
I think there's a kind of confusion regarding what you are pricing. If I sell at retail, I'm really being paid for two things. I am paid for my artwork, and I'm being paid for retail work.
I don't want to sell retail, because depression doesn't allow me enough mental energy to do what's necessary for that kind of aggressive work (I don't mean aggressive selling, but marketting). I'm aiming at higher priced gallery sales, where people bring money and professional sales people sell it. So I want to spend my time and energy making things not selling things.
So what I'm being paid for is the art. And for making artwork I expect to be paid for my materials at premium price, but expect to pay much less for it, through wholesale, smart buying or whatever. I expect to be paid for my time, based on the time a professional would take to make this piece (otherwise I'm expecting the customer to pay for my training, in effect). I expect to be paid for other direct costs of making my product -- gas for lampworkers, needles, etc. I also expect to be paid for artistic merit. For how much I like it.
If I were selling it retail, I'd do the standars conversion from wholesale price to retail price. I'd double the price in order to pay for selling, for maintaining a "storefront", for mailing, etc. That is the standard, expected cost of retailing. That is a profit I'd make on my selling and marketting skills.
For auctions, one would start with wholesale, add direct marketing expenses, and cost of your time marketing, and hope it gets bid up to retail.
There are lots of moe complex descriptions. And this is just my opinion. But it makes lots of sense to me.
Tina