I mainly fix them in my spare time.
usually if the electronic device is more than $10 I will repair it. (done many cheap radios, powered speakers and other random items, it is fun to do and it saves you money)
If the SOC is still working then replacing passives is often easy and cheap, and you get to use higher quality components, eg instead of crappy 85C 1000 hour caps, you can throw in some 125c 2000 hour caps or even some 10,000 hour caps with lower ESR.
and if you are lucky to get custom firmware that actually unlocks overclocking, then you can add a nice heatsink while the unit is opened and not only enjoy your repaired router, but also enjoy it overclocked.
(fun back in the day with the WRT54GL, I eventually repaired it because it started to randomly reboot, replaced some aging caps and also used a higher quality power adapter)