Here's a good spoiler. While on Dantooine explore around the grasslands outside of the compound. You'll eventually find it.
It's called the Crystal Caves. Inside you'll fight a few arachnid like creatures but once you reach the large chamber you have unlimited lightsaber crystals to upgrade your lightsaber with. Be aware you only need three crystals to fully upgrade you lightsaber, but the upgrade is worth the time to search for the Crystal Caves. Make sure you get enough to upgrade Batillia's lightsaber also, it only requires three. Thought this would be a helpful spoiler for everyone. I'll continue to post tips and spoilers as i come across them. JediJosh80