Have you ever thought about this possibility? Well this is it: as3xls is a cool library that enables you to import and export xls and CSV files. It can be extremely useful to your needs!
Here some little tutorials.
Here the examples (google code link is broken!).
And here and other version of the same lib, but in this one there’s a fix for the number of rows you can import. I highly suggest you to use this one then otherwise you’ll get stuck after just some thousands… ;)
Hopefully I’ll post some personal examples soon.