I've come across a couple of different approaches...
1) Based off of the Glass program at Alfred, while I was in school, professors were suggesting $15/h for BFA, $50/h for MFA, $100/h for a fine arts professional. Pottery can sometimes fall into these fine arts brackets, and sometimes, not. This labor cost would then be added to a materials and process cost (including firing and so on) and that would be your wholesale price (double it for retail). This would be a piece by piece analysis appropriate for larger or more time intensive work, but can apply to production work also.
2) I know some production potters that set a weekly gross wholesale value of work. In this case, $1000 a week. Say they work 3 days a week or 60% of their work time in the studio, to allow for marketing and otherwise in the remaining time. They would have to meet a daily production value of $333. Assuming this potter only made handled mugs with trimmed feet, and the market can handle a modest $18 a piece ($9 wholesale), He's looking at 37 pieces a day to meet the $333 daily production value, round up to 40 to account for error/ defect. He knows he can do these handled mugs with trimmed feet at about 10 minutes a piece, so that 40 mug a day order comes out to just under 7 hours of work. In this case, his mugs are a good investment in terms of the return on his time, however other items will be less efficient, and it'll all balance out. This is an easier way to set production goals and make sure that you're on track with supporting yourself.
3) When you access specific markets with your work, your vendors, whether a top gallery or a kitsch gift shop will be able to advise you on what the market can tolerate in terms of price hiking. Make as much as there is demand, and let the work take care of you... This requires making extremely refined objects that fit the market perfectly, and at that, there's not always enough demand to make work "on the fly" like this.
Another consideration I have when developing new work is that the prototypes are always worth more than the final production work. They take more time and often require more labor, while I pare down the process to how I produce the final product. Commonly because of this, early work in a production line becomes gifts or part of my private collection, or the studio kitchen's collection.
Either way, everybody has their own approach, and are often pairing their income with another source, or whining about how tough the life is. I have the utmost respect for those that make it by on the sales of their work alone, and know plenty of potters that would be able to if my pockets were deep enough, though!