Aluminum Bottle at 3 yr. Point.....Test or just replace?

[G-man]

Hi Gang,
I have a small aluminum bottle rated at 4500psi but never filled above 3000psi. (marauder pistol). I have a dive shop near me that tests for $45, though I'm not sure how high a psi they will test, and if price is tank size dependent.  Should I just replace it since a new bottle is roughly the same cost or can I inspect it for corrosion myself and feel safe if it looks good since I onlytfill it to 67% of its rated max. pressure?

[Motorhead]

Inspect, no interior discoloration, no scale but clean & shiny ... use it IMO.

[Back_Roads]

 X2 Inspection at home is fine with the small bottles and air tubes.