"Microsoft Windows 8 32-bit DVD - OEM" is £77 GBP (~ $120 USD).
Prices include "sales tax" known locally as VAT.
Windows 7 Home Premium OEM = 55 GBP ex VAT
There are a number of Win8 upgrade restrictions in the UK AFAIK including you can only upgrade retail PKUs (not previously purchased OEM ones). The deal is 25 GBP for the upgrade.