Hello Pete
I am not a pro but I am fortunate enough to a pro at one of the clubs I belong from whom I have been able to learn during several shows that we have both attended. My method of pricing is basically to look at what more experienced club members (who have also learned from the club pro) are charging for similar work. If I am not sure, I can always ask him for advice.
Firstly, it is unlikely to be possible to predict what will sell. Sometimes, it is all small stuff and sometimes it is all big stuff so a range of work is advisable.
Secondly, it is good to have a crowd puller; something big and showy to attract the punters to your display even if it carries a high price and never sells.
Thirdly, I have seen some good turners who display multiple copies of the same type of work. For instance, at one of the Christmas shows around here, about eight big chunky ear ring stands were on display. I would have left over half of them in the box under the table ready to display should I make a sale.
A friend of mine who is also useless at pricing his own work has to be encouraged to raise the price of his very good quality work. More often than not, this results in a sale. Another friend used to do a monthly craft market and one day somebody advised him to raise his prices. He did so and from then on, his sales were a good bit higher. Pricing too low is just as bad as pricing too high. I have heard of an ex-member of one of my clubs who used to sell work at less than cost.
Joe Public is accustomed to going to a market and if something is cheap, they expect it to be rubbish. The same goes for our work. If it is too cheap, he thinks it is rubbish.
Using the materials, time taken and other costs approach works up to a point. What might take me four hours to produce may only take an hour by a pro. Putting the real time into the equation and I would probably charge too much. There is a subjective element that cannot always be accounted for in a formula and that is the material. Joe Public may be happy to pay a higher price for work made from a particularly attractive piece of timber, especially if it produces a natural edge bowl, than they would form a less interesting timber. I have seen this time and time again when punters are queuing up to pay for work made from a manky old bit of timber, the mankier the better. It is like that on some days.