Lightsaber Color Crystals?

Newb Question:

Where/when do I get to choose color crystals for my lightsaber?

Are they particularly rare/expensive?

They're craftable and can also be found as random drops. Some colors are easier to get than others.

The same color crystals can be used for moddable blasters as well btw.

They are not particularly rare, but the majority of them are crafted. There are some quest rewards, but not too many. You could look at buying some from the Galactic Trade Network (SWTOR equivalent of an auction house). Usually low-level ones are very cheap.

You can change out your color crystal by CTRL + right clicking the weapon in question and applying the new crystal. Be aware that you can remove the old one first and keep it by right-clicking it, but this will cost you some credits. If you don't remove it, it is destroyed when you slot the new one in.

Hope this helps!

Very helpful response! Thank you!

The colors you'll have very easy access to are green, blue, and red. By mid 20s you'll have easy access to orange and yellow crystals. Purple was gotten from PvP frequently (not sure if they changed that since beta). Other colors like black cores (minus the Pre-Order crystal), or white, are very rare and hard to find.