The only one up on the Item Trades is set to a frankly ridiculous price...

You can find Lazulite in Explore. It's not that common, unfortunately. I don't know if it's more or less common in some environments; there are island and explore guides that might tell you if that's the case. 

Since it's rare, you might want to build a Lazulite golem to help build up Lazulite. (There are usually blueprints up for pretty cheap in Item Trades.) You have to have 25 Lazulite to build it (and a pet with 50 Intuition), but over ten days it will produce 50 Lazulite, so you end up with double the amount if you're willing to wait. 

(A Worker throdama or a dragon with Artisan will save a couple of lazulite from the original 25 without changing the number you get from the golem later; that's not essential but it's nice if you can get a pet like that.) 

Thanks :) I wanted the Lazulite in order to make the golem so I guess I'll just have to buy some... eventually.