I would get a jango helmet, due to the fact that boba helmets are defined for boba, some have a wavy brown but all have the dent. however sgt.fang has a great deal right now in the cargo hold, I would grab one of his and fill the dent with some bondo.
At this point I would do what Zombierepellent said go with one of the Sgt. Fang helmets they are Boba helmets, but they are full sized, the dent can be eaisly filled, and they are at a great price right now.
And cost is an issue as well. If you have the funds get a nice fiberglass one (My fav) or if money is tight, start with a cheap Don Post. I feel the helmet is the most important part of the armor so I'd save some money and get the best possible and work your way down from there.