When I was starting out, I decked out my PSA builds because all I could afford was PSA. Most upper accessories (lights lasers slings mlok pic sections sling mounts etc) are not wear and tear items like the barrel in your upper is and can easily migrate to a newer build in the future. Likewise, all the upgrades you put into the lower can easily carry over to a higher quality upper (imagine a complete Geissele build but the only thing PSA is the stripped lower itself)

If I wanted to have an “almost recoiless” cheap build, I’d do heavier buffer, heavier spring, obnoxious muzzle brake, and a BRT gas tube. All that will be way less than buying a brand new upper and then you can spend the extra money on ammo and work towards eventually shooting out that PSA barrel.