How do I get a business proposition out there?

Oh, forgot to add bobtheodd is right about Facebook also. Be sure to join some of the customizing pages there you can post your stuff on those as well. More exposure = more buyers and more commissioms. Just be sure with commissions you agree on the terms and get at least the $ for materials up front. A paypal account is useful for that. If you don't get the money and agree on terms. The client could bail on payment or decide they want a ton more stuff done. Then it's a fight to get paid and you may end up eating the cost of a custom!

When I get my site up and running again, there will be a free adspace for customs. Ebay is a decent option, especially if you list under custom marvel legends or are making T-Formers under that listing. I would recommend places like ecrater or ebid as well. Do as many sites as you can keep up with. You could showcase your stuff for free by setting up a webs.com or similar free host. Many customizers have used webs.com as their host. You can always link your other sites back there for more pics of your work. A facebook and twitter account are also useful. Blogger is cool if you wanna do a WIP type setup. Deviantart is a useful site as well and there is a special group for customizers. Then you have marvelousnews.com , actionfigurepics.com, etc. These sites will spotlight work sometimes. Joining the customcoalition allows you to put a banner to help build trust with buyers. Then you have sites like thefwoosh, actionfigureblues, thundercats.ws, tfaw2005, hisstank, customizerproboards, and others that fans and enthusiasts follow that allow you to setup a thread for your work. Not as great as figurerealm but they have brought me commissions here and there.

Sounds like a plan, I was debating craigslist, but felt the market there would be way to broad and unfocused. A facebook page it shall be... now to think of a good name for it...

Easiest way would be to start a Facebook page(cause almost everyone and their mother is on there) to generate contacts. Join groups and showcase your stuff. Sell a few that you have made, or at least offer them for sale. If they are good then before to long you should get hit up for commissions.
Thats my 2 cents.