Vita card prices are still an outrage five years after launch, with no low-cost third party options to take the sting out.
Here are the current prices around the net. If you see a bargain on a particular site, do comment. Remember 4GB cards aren't worth owning, unless you can get one free. While 64GB cards all ship from Japan as they were never released in the west, compounding the ignominy of owning a Vita.
Gamers have various problems with Vita memory cards, some can be solved be removing and reinserting. Others like PS Vita error "C1-11834-7" are often an easy fix, while error C4-10278-8 looks like you may need a new card!
On Amazon for the US:
And Amazon in the UK: