My boots are cracked but not completely through yet...here the options I have come up with.
1. Order the "evil" split boot from Cosmos International at 1-800-221-2668 at about $20 bucks, and install. Hopefully it will work ok, and last awhile.
2. Order two axles from advanced auto for about $110 USD each and change them both at once, yourself.
3. And I actually thought of the same temp fix you seem to be wondering about. I figure I'd go to walmart, buy the largest diameter bicycle intertube and some type of glue, cut the old boot off, overwrap it twice, and cable tie and glue it together. What do you think?
PS You might want to wrap the boot with plastic wrap and tape until you figure what to do, if you have to drive the car.