Basic Tesla Shop Guide

All the materials required in the Tesla Shop can be obtained by leveling up characters, doing achievements, disassembling items, or getting the hourly supply box (the box gets better materials if you win any game type).

Normal Tesla Shop
Two possible materials you can get for the Normal Tesla Shop is
purified ore

and ore

You can combine ten ore into one purified ore. One tesla use requires seven purified ore. Premium Tesla Shop
The same happens for this shop, except it's
crystal

and purified crystals

The items in the tesla come in batches of 200. Out of those 200 items, only one of them is the permanent weapon you want. The fraction represents how many items are left in the batch out of 200. If you use the tesla and get the permanent weapon, the item batch will reset back to 200/200.

For example, if you try to use the normal tesla shop and the weapon you want is 100/200, you have a 1/100 chance to get the permanent weapon, since 100 timed weapons were given out from that batch.

PLEASE NOTE: not all of the items in the 200 batch are the one you want, they stick a bunch of weapons from other classes in there as well.

For the premium tab in the tesla shop, there is something called a fever bar. The more you use the premium tesla shop it gains more and more fever, which is a mileage point.

(edited, developer corrected me :D)