1. I need level 4 locks they are hard to find
2.Same as above but with dark matter
3. Best place to level up?
Thanks im new :P

Where are you up to in the game? Would help us answer without spoiling it. :p

I can go anywhere besause i have finished the game just trying to beat the dark aeons now

Did you find the Omega Ruins yet? If not then search on your airship around X=71 Y=35 or somewhere around there. In terms of a best place to level up, that's probably it, and you might get a couple of lv4 key spheres in there too.

Otherwise, the only other way to get lv4 key spheres is to bribe Chimera Brains on the Calm Lands - pretty expensive, it took nearly 200k to get two if I remember right... but you shouldn't need too many more of those than the game gives you anyway.

If you want to take on the Dark Aeons you'll need to complete the monster capturing if you haven't already and that'll also give you a much quicker way to level up too as you get some nice items when you complete areas.

Once you capture every eyeball monster you'll be able to fight a One-Eye in the arena, if you beat that you might get some weapons with Triple AP - the character dealing the final blow has the best chance of getting a weapon but it could be for anyone. You'll want ones with Triple AP and two free slots.

In one slot you'll want to put Overdrive>AP, which you can get from Door to Tomorrow which you'll get after capturing enough monsters to finish a few areas. After that you can add either Double Overdrive or Triple Overdrive - obviously the latter is better but you'll only get the item you need for this once you've captured 10 of every enemy in the game. If you found all the Al Bhed primers Rin should have given you Underdog's Secret that can at least make Double Overdrive.

Now give one character Stoic and the other two Comrade overdrive modes and fight Don Tonberry - if you already finished capturing it'll be available otherwise you just need to get one of every monster in the Cavern of the Stolen Fayth. Attack with the character with Stoic and it'll use Karma, revive them and attack again and again until it stops counterattacking, at that point you might as well run away. Now with the Triple AP, Triple Overdrive and Overdrive>AP, every time your character is hit all three should be seeing their overdrives overflow, which is being converted directly into AP. You should gain 60-99 sphere levels in a matter of minutes, and then you cna just repeat over and over. :D