That's the average price over the last couple of years, but since January they've been £29.99 for 4, except for a few spikes https://uk.camelcamelcamel.com/product/B0875CTMGH Going rate is £8.99 each, £15.99 for two or £29.99 for 4. If they're more expensive than that, wait a week
This is Amazon's lowest price historically (according to camelcamel). The price yo-yoes crazily but camel shows an average Amazon price as around £42.
This is the standard price for these from Amazon, bought some a few weeks ago
Perfect timing for me, thanks, as I move house on friday and was needing these!