Based on your question, I'm not sure if you already have access to wholesale items or if you need to know how to get a tax ID number in order to sell them at a higher price elsewhere.

If you're already selling and making small profits off of eBay sales, your social security number is a suitable enough tax ID number. But since eBay has its own policies--and since the IRS's policies change as legislation changes--you'll want to familiarize yourself with eBay and the IRS by going to their websites and reading the fine print.

Also speak to your accountant--as you may have sales tax issues (for which you need a special ID number for that) in connection with the collection of sales tax on the items you're selling.