Epoxy primer is superior to etching primer no doubt about it.
Shoot 2 coats of epoxy over the bare metal. Finish it off with a coat or 2 of urethane primer. Then topcoat with a ss urethane.
Use a cheaper line of paint like PPG omni. Not long ago I paid $80 for a gallon of Omni ss urethane that I used on an old pickup. Not bad stuff for the price.
For what you are wanting to accomplish, you must topcoat this car.