I haven't had a chance, yet, to sell a whole bunch of pens. I have some pens that won't leave my table for anything less than $50.00 and those are the ones in the middle of the pack as kits (i.e. Cigar pens, Cosmopolitans etc.). I could be way off but like I said, I haven't sold a lot yet.
PSI has a pricing tool on their site by each kit but I never go by the highest price, they're usually way off. I go to the middle of the pack and adjust to that. The other question is what venue are you selling too, Etsy, Ebay etc? I've found on Etsy and Ebay many pens are way under priced and the maker is barely covering their costs. People leave out the cost of wear and tear on their equipment let alone component parts (like band saw blades). Lathe's don't last forever and it's always nice to have the cash in your business to replace it with the funds you've gotten from selling your products. That's how I run my small business.
I sell more knives than pens and here's how I price them. I take all my costs, knife blank, scales, epoxy, pins, sandpaper, finishes-you get it, add those all together and come up with a cost per knife less my labor. My labor I figure at zero, some will disagree but in my eyes, it's still just a hobby. I take that final cost per knife and for wholesale I take that cost and multiply it by 3, for retail it's 5 times.
As an example, if I have a blank that costs, say, $20.00 and all the other stuff added up equals a cost of $5.00 then my cost for that knife is $25.00. Based on my calculations my wholesale selling price is $75.00 and retail would be $125.00. I spend around 10-12 hours per knife, sometimes more, you can figure out my labor return. Hope this makes sense.
I don't sell through Etsy as I've found it to be a format that doesn't match my philosophy on selling. When someone on Etsy sells a nice slimline pen for $20.00, in my opinion, they're underselling the market and hurting every other turner. Don't be afraid to charge a price you're happy with. Barry Gross made a statement about pricing, darn wish I could remember it, but basically he states don't under sell your product just to make a sale.
Mals info above is spot on.
Hope this helps.