Starting on Friday March 18, there's going to be an estate sale in Naperville where there's going to be a lot of vacuum tubes available.
More info here: https://www.estatesales.net/IL/Naperville/60563/1130091
Etymotic will replace the broken driver for $80. Even with the high shipping, it's still a good deal. Also, changing tips can improve the bass. I use Klipsch tips with mine. Shure olives are also very popular.
Etymotic won't fix your headphones but will send a new pair if they're under warranty. For out-of-warranty phones, there's a program where you can buy a new pair at a discount. http://www.etymotic.com/cs/