I guess I'll bring it back on topic, since I didn't see anyone mention it over 7 pages of arguing. (Hopefully I didn't skip over any real posts!)
OP, you had your answer in your own post. Part of choosing a selling price is choosing your customer base. You chose it (I assume you fit in there somewhere), and you have a general idea of what it would be worth. You want to take the amount you think they'd pay, the amount you'd like to make (the key is this number should be at least a little profitable), and meet somewhere in the middle, preferably to the higher (your) side.
My guess is you came up with $18 bucks somehow, and you're not really undercharging. I think your post indicates that you are looking for a reason to give yourself a raise though, and I think you know you deserve one, so go for it. Just remember to keep it in a range that will keep your employers happy, and they'll be fine with it too.
OP, you had your answer in your own post. Part of choosing a selling price is choosing your customer base. You chose it (I assume you fit in there somewhere), and you have a general idea of what it would be worth. You want to take the amount you think they'd pay, the amount you'd like to make (the key is this number should be at least a little profitable), and meet somewhere in the middle, preferably to the higher (your) side.
My guess is you came up with $18 bucks somehow, and you're not really undercharging. I think your post indicates that you are looking for a reason to give yourself a raise though, and I think you know you deserve one, so go for it. Just remember to keep it in a range that will keep your employers happy, and they'll be fine with it too.