I so adore begonias! And just this past year I found out it is not hard to over winter the tubers/bulbs. I've always grown the upright varieties. I will have to get some hanging ones next year! I know just the nursery to find them.
I bought my tubers online on sale one year. If You're interested, I'll try to look up the website. Begonias do such a good job of brightening up a shady area!!