Where should I get Chain Kerbeus? At mall of toys the guaranteed is 48$ and out of stock. When it’s restocked, will it go down to a less inflated price, or will it just keep getting higher. How to I get my money’s worth? Should I just buy a full set, or should I get it from somewhere else.

In my opinion the best way is to buy the full set and sell the beys you don't want to break even or make a little bit of extra cash

Where should I get Chain Kerbeus? At mall of toys the guaranteed is 48$ and out of stock. When it’s restocked, will it go down to a less inflated price, or will it just keep getting higher. How to I get my money’s worth? Should I just buy a full set, or should I get it from somewhere else.

Your best bet is to buy the full set, since it has two prize beys (Kerbeus and Driger) you should have an easier time making some money back by selling Driger.

Alternatively, if you care more about getting the parts for their competitiveness, you could try to find someone selling the recolored Kerbeus parts (red chip, blue layer) and Fortress, although I don't think the RB has an extra Yard' if you want the full combo.