You have to google the net for the best offer. Logically, they are most in demand during a heatwave, so you might want to look in autumn/winter, because the next heatwave is sure to come.

Due to the enormous number of sales in recent weeks, we can now only fall back on an enormously expensive offer from one supplier.
As soon as the other suppliers are able to offer the item again, the price should normalise. However, we have never been able to offer a price of 890.