Hi Ricardo, $300 is insane money for four cylinders. As I wrote, I tried to get cylinders from Stevinson. The add-on to that is they took my order, but I didn't find out until a week or so later that they found out they are no longer available. For new cylinders, I'd go with either Mark's Off Road or CCOT. I trust both of them.
It's up to you - swapping front disks is a nice upgrade in not having to adjust, but for the money I'd just go with Mark's or CCOT aftermarket cylinders..