Custom Anime Painting/Artwork Costs?

So I have a favorite anime (I'm a Redditor, what else is new) that really relates to my enthusiasm for MMA, especially when I find time to go to the dojo/gym to learn something new (I also do amateur MMA fights), but I can't find artwork for it anywhere

I would like to gather all the main martial arts master's totalling about 10-20 characters of various fighting styles including the main character within the anime and have a customized piece done. Preferably about 24'"x36", but may settle for 18"x24".

The anime is: Histories Strongest Disciple Kenichi -

Anyone know what this should run me so I don't get ripped off?