Definitely none of those. Moar platez, is the first thing I would consider. and/or an upgraded barbell / rack / bench, depending how good those things were to begin with.
A nice pair of spinlock DBs, perhaps. Gah, so many other things, actually...
^ The prowler idea is nice, too.
Squat 160kg (352.7lbs), Bench 115kg (252.5lbs), Deadlift 220kg (485lbs)
Front Squat 130kg (286.6lbs), Strict Press 80kg (176.4lbs), Chinups +30kg (+66.1lbs)
My training log