You could setup a personal mail server at home, I used Sendmail but Postfix is good too. Have it pop your gmail account every two or three mins or whatever you're comfortable w/. When it receives mail, (I'd advise through the use of a filter only) have it send your filtered messages as a forwarded email to your txt number @ phone address.

Even better, you could build a perl script to hand deliver the filtered message to a different address so it isn't forwarded but just redelivered to your sms box.

Or, drop the number of minutes on your plan to a $20 dollar less expensive minute plan (if it's available) and add in the data plan, then do everything you can through various data options, email, goog talk, etc.