Normally around £25-30 so bargain at this price. £2.99 delivery if your order is under £20 but free click and collect.
You could also get the CG2 kit for £20.99 which includes a cassette cleaner and bottle of degreaser (RRP £34.99) and would qualify for free delivery.
Park CG2 Kit (includes CM5) - https://www.evanscycles.com/park-cg2-chain-gang-chain-cleaning-system-ex-display-EV290322
A chain cleaner is a must for anyone clocking up regular high mileage and this is probably the best on the market. Park Tools stuff isn't cheap but there's a reason all the bike shops use it.