Toyota Repair: Shift solenoid valve E, solenoid valve, metal shavings

Question
My check engine light just came on for the first time in my 2001 Toyota 4 runner 4wd with 206,000 miles.
Code diagnosis Shift solenoid valve E
4 runner seems to run fine
What is the approximate cost to repair parts and labor by an approved garage?
Is it difficult to repair myself?
Should I just replace the entire transmission or purchase a used one for replacement?
Can I continue to drive with this problem or should I have it towed to my garage?

Answer
The shift solenoid "E" is the lock up torq converter solenoid, in most cases this is beacuse particles in the fluid are clogging the solenoid and replacing the solenoid is not the solution, I would recommend trying to have the transmission flushed using a fluid exchange machine, this replaces all the fluid and removes most particles, it may be worth the $130 or so. If the transmission has shifting issues then removing the oil pan and inspecting the inside for metal shavings and friction material may be necessary to confirm that it is a transmission problem. The vehicle can be driven in this condition unless it is slipping or otherwise undriveable.