As grunt_king11 said, There's no official 1.8 Spigot update yet, so we are using something called "protocol hack builds", which are specified java modified builds that ALLOW 1.8 CLIENTS TO PLAY IN THE SERVER and that's it, as 1.8 features aren't out yet. Therefore, it blocks all 1.8 activities such as the new enchantments prices.
This will be fixed soon, when we fully update to 1.8 (the update is almost done, don't worry
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