$3 coupon for Silicon Power products (checkbox under the price on the listing page) reduces the price to $43.99, which seems to be a reasonable deal for a 256GB Micro SD card.
17.2 cents/GB, which is a little more expensive than the current 400GB Sandisk Micro SD deal ($0.17/GB)
Edit: Coupon doesn't seem to show up anymore, which doesn't really make this a good deal. As such, I've marked the deal as expired.
Is this good for dashcam? I bought a b1w dashcam and sometimes it stops recording and someone pointed out that I might be using an ordinary SD card (it came in a bundle).