Hi, Gwen.
Glitters2004 is right - being in business is not easy. I took my hobby of silk flower arranging to a business, then added jewelry making to it, just over a year ago. I only sell at a monthly trade fair and just made my first, very small, profit last month. I love what I'm doing, though.
On the down side, I'm always working on the next merchandise for my booth, thinking of new ways to market myself, trying to come up with ideas that will get people into my booth and merchandise moving out of it. Over the winter, I sold only jewelry. For the last three or four months, I've sold a lot of silk floral arrangements, and not much jewelry; there's no predicting what people will want. Spending time preparing for next month's sale means the house doesn't get cleaned like it should, laundry sometimes piles up, etc. There's always paperwork to do - inventory, pricing pieces, paying bills.
You'll have to check into sales tax and licensing requirements in your area. Texas believes that if one sells two items in any 12-month period that one is in business and needs a sales and use tax permit (let's hope none of the ebayers get caught) and is perfectly willing to find anyone who does get caught something on the order of $100 per day from the time of the second sale until the permit is applied for. If you want to open a business checking account, you may need a "doing business as" statement, if you're not trading under your own name. Fortunately, I found out, quite be accident, that I had to file a "business personal property tax rendition" (form indicating how much inventory I had on hand as of Jan 1) before the due date for filing.
Having said all that, even with all the work involved in setting up a 24x24 foot space by myself every month, I am having fun doing it and it's obvious to the vendors around me and to people I talk to about my business that I am having fun - it's not just something I say. There's nothing to compare to the thrill of hearing "you do beautiful work" and selling something you're made.
Your aunt has a good idea - even if you don't want to go into business right now, if there's a name you like, you might as well reserve it as a domain name so you can have it if you do decide to go into business. Business cards can be done on most home computers with business card stock that can be purchased just about anywhere. I'd definitely make up some business cards - even if you just give them to your aunt to give to her friends.
I hope this helps.