Try the app at bitpim.org  With a USB cable and bitpim, you may be able to dump all the text messages to a spreadsheet.

And just a bit of advice...if your business is so dependent on archiving electronic messages, it may be worth your investment in a device that will do just that.  And I wouldn't save 2 years worth (I'm not even sure the Touch can save that many; my Voyager would delete the oldest if the "inbox" got full).