i don't know the cost, but imho, it's not worth paying to upgrade your TPA-MSP and DTW-TPA segments. you'll get a somewhat wider seat, maybe some more legroom (depends on your Y seat and aircraft type), and free alcohol (but you'll also be getting that on your international segments).

as for your AMS segments, those are not upgradeable using e-upgrades at the kiosk, but on rare occasions, GA's have been known to sell WBC upgrades at the gate for transatlantic flights, usually for $250-500 per seat.