For a few "popular" random examples that I think HN might have heard of: one branded Epi-Pen is £26.45; Naproxen (the NSAID painkiller) is £4.29 / 56 pack; and omeprazole (PPI used to treat gastric reflux) is £0.84 / 28 pack.
A more expensive example might be the cystic fibrosis "designer drugs" lumacaftor with ivacaftor -- 112 tablets are £8000 (to be prescribed by a specialist, if the patient has the genotype to respond to it -- a total annual cost of about £26k). The US equivalent is $379,780 [1].
(NB: The price you pay as a British patient is usually £0, unless you are a working-aged and working English person -- at which point it is £9.15 per item [independent of its cost] or a fixed "all you can eat" prepayment certificate that works out at about £8.83/month -- which is what I have. Oh, and plus the taxes, of course...).
[1] https://www.jmcp.org/doi/pdf/10.18553/jmcp.2018.24.10.987