There is a reason the official one sold in wal-mart stores is $50. This microSD card does have 256GB of storage, but it is also faulty. You will have problems downloading games and you will encounter problems with corrupt data. At most, you will only be able to utilise about 40GB worth of storage before problems start cropping up, making the card unusable without re-formatting and losing all the data on the card. For the same price, you can buy an actual 64GB mircoSD card and get far better value.
At least, this is the conclusion I came to after buying two 256GB microSD cards from this provider, with the second one being after I returned this one for being faulty. The moment I put the official one inside the switch, all the problems dissapeared.
You will get 256GB of storage with this microSD card, good luck trying to use it though.