@BLuFeNiX With the plugin working now, I'd like to make a few suggestions / requests if you're open to it.

• YML option to customize the book and scroll recipes. Since my server is well past end-game, end pearls are readily abundant and easy to acquire. I'd like the ability to modify the recipe to include components that are a bit more work to acquire (ie: ghast tears) or require more of said materials (ie: eight pearls and a book vs just one).
• YML option to modify the "charge up" time before the teleportation occurs. Optionally make it a customizable calculation based on distance being travelled (the way you do with cost).
• YML option to disable or change the teleportation effects (specifically the lightning). I happen to like it so far, but I can also see it being an annoyance to others. An option to have no sounds / effects, or alternatively use the endermen swoops, upon teleportation would be appreciated.
• Haven't tried yet, but does teleportation work between worlds? If not, please? Add a YML configurable 'additional charge' (and additional charge up time) to the calculated teleportation cost.
• Cost calculation, can this use any basic math functions? Ceiling, floor, absolute value, modulo?
• And just for some OPTIONAL random teleportation shenanigans / player torment... a configurable (distance influenced) random chance the teleport will 'malfunction' and 'drop' you somewhere part way between origin and destination. Hey, this a faster alternative to nether highway travel, but since magic is involved, use at your own risk, MWUAHAHAHA!!

Thanks for all your work on this!

@zaphiredfox These are great suggestions. I've considered a couple of these before, but you have some cool new ideas as well! I think these are all doable, and I will try to start working on them after I integrate the FreeBSD branch into master, which shouldn't be too much more work.

As for the cost formula, it's powered by exp4j, so it should support all the functions listed here, but I have not tested any of them myself.