Cheapest Piece of Equipment to Upgrade?

With the exception of Occult cubes, they can only be obtained from the Cash Shop with NX.

Im fully aware of that, but Im asking OP if he obtains cubes through mesos from others or buy his own cubes with his own irl money. If its not too hard for him to get cubes, cubing for decent se or max crit dmg on glove wouldnt be a bad idea. Obviously that sounds like a big investment, but its one of the cheapest way to gain a pomegranate load of damage on a demon slayer, seeing how they have around 200% total dmg/boss dmg w/o potential (including links and char cards obviously).