You EIN is simply employee identification number. It is used by most companies to report your earnings and taxes for state, federal, workman's compensation. Most all companies use your social security number in this capacity. A few of the larger companies will assign a second number also.
If you filed a dba with you local government and are doing business as a sole proprietership, and have registered you business name with local and state government, you can attempt to use your ssn along with copies of you dba certificate to provide proof to the companies that you are attempting to deal with that you are a legitimate company.
I have came across only 2 wholesale companies that accepted this. But I'm sure that there are probably more out there. However I would make sure that I explained quite clearly to these companies that this is what I am using and type of business (sole proprietership) I am operating under. Most legitimate companies will check the number (reseller permit) to see that you are in fact authorized to purchase good at tax exempt.
Also some states require additional reseller permits in certain catagories of goods.
My state issues only one permit, but when you apply, you select all the catagories for the good which you will be selling. When a business does a check on your permit number all of the approved catagories will show attacted to that specific permit number..
I would suggest that you go ahead and just get a resellers permit. It is very simply to get and will return great benefits. Most major 'TRUE' wholesalers will require this permit. These are the ones that will be selling branded and high quality goods...