>>290056703
Don't listen to Mr. Moneybags. You can probably find reasonable rates for a custom or customized avatar in the few hundreds range depending on what specifically you're looking for and who you commission. I can't say I know any good services or communities for finding a modeler though, so you may have to ask around or do some research.

Make sure to ask to see samples or a portfolio if you want more than someone shit rigging an MMD model for you; I've see a lot of work that's looks [spoiler]worse than my scratch work[/spoiler] pass for way too much money online. Still, offer a fair price and you've got good odds of finding someone who will do fair work.