In order to buy wholesale you must have a tax id. In order to get mine, I had to obtain a DBA (doing business as) certificate from the county courthouse (the same office from which you get a marriage license). Then I went to the Tax office and applied for a tax id. From their website you can get more info and find a location near you: http://www.window.state.tx.us/taxinfo/sales/index.html
Hope that helps!