In the Adobe website, there is an online shop sample. But problem is it is driven by static XML data. The question is: is there any really sample that people use it for their own shop. My answer is YES.
Here is a sample application that a professional Photographer use it to sell her own photo and service.
Here is the links:
Front: http://exdoo.com/clients/andy/fotocrystal/webstore/webstore.html
Back: http://exdoo.com/clients/andy/fotocrystal/textileadmin/TextileAdmin.html
The back end of the online shop is PHP+MySQL. So, as a conclusion, the solution is: Flex+PHP+MySQL
For further sample that us know, please visit http://exdoo.com/links.html
Hope this is helpful to you,
Jackie