I've got a lovely new 5gal now, courtesy of my father.

My friend says she will give me her 10gal and equipment, which would be very nice for split housing my other two. And the 5gal sits there . . . beckoning.
Call me obsessive, but really.
I could take it back to the store and ask for Dad's money back, but it's just so convenient, especially since I recently fell in love with the picture of a betta being sold online. She's pricey, but I want her SO BAD. I'm torn between the practical, adult side and the MUST-HAVE-IT-NOW side. I'm much more responsible than I was and I think I could take good care of her. What do you think: return, keep it and find a guy in a store, or order offline?