I should have been more specific, I meant the Mod Ideas sub-forum (for Medieval II), which is here, probably the best place to put forth your unit pricing plans:
http://www.twcenter.net/forums/forumdisplay.php?f=428
There is also the Mod Workshop, a good place to ask and answer modding questions (you could present your idea there, too, probably in the text editing section):
http://www.twcenter.net/forums/forumdisplay.php?f=272
And welcome to the twc site. Most of the entire site is one big modding discussion forum!