Pricing caricatures?

[JayzusB.Christ]

Not sure if this should be in the Help section, but I thought that people with the relevant experience would hang out in this section more.

Anyway how much should I charge for commissioned caricatures? (In your own currency, I can convert it to euros myself).  I have a horrible tendency to underprice, I think, but am never sure how much it should be.

Here's two pictures I posted in the art thread - the pencil one isn't a caricature of course but it's in the same style I do pencil caricatures.

Thanks!

http://www.2000adonline.com/forum/index.php/topic,27612.msg530410.html#msg530410