One of the best and least expensive places to purchase your launch rods?
Your local steel supplier.

Can get aluminum, stainless, rolled mild steel in all different sizes up to twenty feet long.
I have some 3/16" rolled steel rod in the garage for a different project.

Tri-Flow is better for wiping than WD40. Has teflon in it to leave a coating on the rod that lubricates, just doesn't protect only from water, dual purpose.

Mike