PriceSpy (price comparison website)

Shrews

Not sure if anyone has used this website before, but just seen Boss Katana 50's are still available at £167, although not in stock until 4 weeks time.

https://pricespy.co.uk/audio-video/musical-instruments/amplifiers/guitar-amplifiers/boss-katana-50--p3902210?gclid=EAIaIQobChMIkIGv3v7R3gIV67XtCh0pIwlZEAMYASAAEgLGnPD_BwE&gclsrc=aw.ds

Just checked some guitar types and there seems to be a fair range where price is compared

fandango

Not that I've used them lately, but don't forget these price comparison/shopper sites:

kelkoo.co.uk
pricerunner.com
nextag.co.uk
and
pricegrabber.co.uk (however surf this one at your peril, my adblockers have flagged/blocked this)