What make/model of 512 SD card did you get? I've just seen this on Amazon and seems a good price (UK wise) Not sure if it matters if its in an adapter or not?!
Micro SD - Integral 512GB Micro SD Card Premium 4K High Speed Memory Microsdxc Up To 100MB/S V30 UHS-I U3 - £58
SD - Integral 512Gb...