Where is it leaking from? I have used Home depot specials all the way to the professional guns (not sure of the brand but they are $100+ )the guys use at work and never had any leak.
Leaks mainly at the connection/hose end.
Do you buy a new house when you get a drippy faucet? Tighten the fittings. If it still leaks, get new fittings.
A lot of it has to do with the grease. Mobil 1 pink stuff separates after time and will find a way to ooze out of pretty much any gun.
That said, if you want a quality Made in USA product that will last for generations, check out Alemite Heavy Duty series.