The best way I've found is to use Link hidden: Login to view
to search for your state website.
Select the website for your local state government.
Then go to the business section and search for reseller tax ID (note you may need to try a few variations as the name varies a bit between states). Often the appropriate forms you need to fill in will be online, or there will at least be a contact.
As for cost, this will vary from state to state.
Hope that helps :D