I know that there are some hammers with the
+ x% Critical Damage stat such as The Colossus, which is very expensive.
Which are the other hammers with the same set of stats of the colossus one ? How do i get to acquire them ?
In GW2, there are a fixed number of different stat distributions available for equipment. The stat distributions that contain +Crit are:
All level 80 Exotic items with a particular stat distribution are identical, with the exception of their appearance. This means that there is no difference between The Colossus of Rage and any other level 80 Exotic hammer in the "Berserker" family, other than the skin (which some players will gladly pay through the nose for).
So, that said, what's the cheapest way to get your hands on a level 80 Exotic Power/Precision/Crit hammer? Here are your options:
If an exotic is too expensive for you right now, or you want something to tide you over while you farm CoF/Arah, you can pick up a rare weapon instead for very little money. The damage and stats are lower, but the distribution (Power/Precision/Crit) is the same.
Finally, you should check out Dulfy's GW2 Endgame Gearing Guide for more information on where to find the various types of gear at level 80.
The best way is probably to go into weaponsmithing, making the right stat thing. And then discovering it, which will give it the stats you want