Returning player....

Crystals are not a good investment since all but the 5 star versions are easily obtainable. You may want to check out the new gunner gear http://wiki.spiralknights.com/Padded_Cap

It starts with the Padded set but can end up resisting any type damage, any or four statuses, as well as providing ASI and CTR on all of them with a choice of universal damage or a Higher family bonus. Lots of research would be needed before fully investing since these are only obtainable from Basil (except the starter set) and they can be easy to mix up.

The wiki says that you can purchase a ticket in the supply depot. Now maybe i missed it , but last time i checked i didn't see it in there.

Knight Name Change Pass is in the Usable (not Ticket) category of the Supply Depot, for 3,500 energy.

Also , im thinking of buying energy . What would be the top priorities to get for a returnee?

As Holy-Nightmare says, you probably don't want to buy fire crystals with energy. The 2- and 3-star fire crystals are not strictly necessary and easy to find anyway. You might want to buy 4-star fire crystals, but I still wouldn't; you can collect them pretty quickly. And heating a 5-star item requires so many fire crystals, which cost so much energy, that I don't recommend buying them either.

Perhaps use your money to buy energy so that you can buy Orbs of Alchemy and craft a wider variety of 4-star items.

What other items would be good to get?

Many items are good to get. Which ones you get first depend on your class (sworder, gunner, bomber, or hybrid), your play style, whether you tend to play solo or in parties, etc. Try reading the Bombing Guide on the wiki, or the Gunslinger Guide, or my detailed sword guide.

Welcome back.

Thank you Boop and Holy - N.