Where do you live? If you live in an area that has some big nurseries then you may be able to find it locally which is the best option - bigger, healthier (usually cheaper) plant that you pick out the best of the litter.

If you don't live in an area with a wealth of nurseries then your only option (unless you travel) is to buy mail order. There are many good growers out there (but there are some pretty bad ones too).

Logee's has it in stock now. You can check on eBay. Use your search engine to find other sellers.

Try this nursery. I've gotten really good plants from them. This looks like Escargot on their main page. http://taylorgreenhouses.com/

Have you tried Accents for Home and Garden, the online division of Pepper's Gardens? www.accentsforhomeandgarden.com/ I am very pleased with their plants, conservative pricing and customer service. They have an impressive, varied selection of begonias grown & shipped in 4" pots. Shipping is priority mail. They are located in Delaware.