Steering issues make me very nervous.
I would spend the $80 for safety, if you are not sure of what is going on and all that might be involved.
saying you have DW, but the principal components that people work on adjust / replace would also affect a vibration issue in the steering-IMO. Might want to read check that thread-may help direct you to what is causing the problem.
Good move on rotation/balance of the tires-might also consider another rotate and balance if nothing is found in suspension steering components. Sometimes they don't get it right the first time.