How do you get a crossbow?

I'm planning on buying Skyrim for the PS3. I want to get the best crossbow possible in the game but I don't know how. But also I would like any crossbow. If you only know how to get the normal one that would still help me.

Solution 1:

You can get steel crossbows from members of the Dawnguard. You can get the ability to craft dwarven crossbows and the enhanced versions of both crossbow types by joining Dawnguard and doing the Ancient Technology quests. You cannot get crossbows without the Dawnguard DLC or installing a third-party mod to the same effect.

Solution 2:

There is no crossbows in Skyrim unless you bought the Dawnguard DLC. Without this addon the crossbows doesn't exists anywhere.

Althought, you can still get them with mods, if you're playing on a PC.