UK RX5xx are in short supply but RX4xx are pretty easy to get hold of, think with AMD actually being able to compete with Nvidia there getting hit from Miners and Gamers so demand is stretched.
Not for us in the US. Price severely gouged on both cards and nearly no rebates or discounts except on the lowest end 400 and 500 cards on Newegg. Miners are the primary demand I expect, as most gamers have already likely bought in the 400 series.