Chad, where does he say anything about 4 flap servos?

I am assuming that you are using 1 servo for each surface.
S3004 on throttle and rudder/tail wheel.
Will retracts work with a standard servo or will they need a special retract 180 degree servo or a high torque? If a standard servo will work, use a S3004 there.

BTW- There are other places to buy servos than Tower you know.