Well, i am not an expert by any means, but this is what I have been told in the past. Take your hours into it, multiply by 5, add your material costs, then multiply by 2.
For example:
$30 for materials
10 hours labor
Selling price: (30 + (5 x 10))* 2 = $160
I have only sold two knives so far, and have given away two, soon to be 5.
Here is what they looked like:
Blade
Handle
Triplets
I sold each of these for $250 and each came with a hand tooled hand made sheath. Each knife took me about 9 hours to make which included the sheath. Four knives came out of the damascus billet, which took me 10 hours to make.
Looking back, I would rather have charged $275 or $300, but hind sight is 20/20. However, I am in a very good position for pricing high. I don't need to sell knives to make a living, which is nice in many ways, but also does not leave me as much time to work on them either. Freakin' day jobs anyway
I would strongly caution you against selling at too low of a price. It can be very detrimental to you and to other custom makers. I would just do a gut check and set the price on what you would be willing to buy it for if you didn't have an emotional attachment to it.
Just my $0.02
What kinda grinder you lookin' to buy? Just curious.
Edited to add:
Here is a link that might help too.
http://www.bladeforums.com/forums/showthread.php?s=&threadid=235363