COR is cheap PUP requires 7,500,000 gil just to pay for your attachements "bro".
1) All the attchments don't cost anywhere near that much in total on Shiva

2) COR dice cost almost as much and only come from NPCs, so there's no chance of the price going lower; COR also has to spend gil on ammo and cards constantly while PUP doesn't. PUP does have the repair oil but that's not absolutely necessary to the job most of the time.