Had same issues mate for a midweek trip we're taking at end of November.
Prices are a piss take nowadays - must've been to London about 30 times for weekends away over the years. Cockneys always did love a rip off, but you could find somewhere nice at a reasonable cost if you looked hard enough. Since Covid though, everyone's prices seem to have virtually doubled. Greedy twats.
We've ended up booking the Travel Lodge at Kings Cross. Its walking distance from Euston, has really good Tube links to virtually everywhere, and isn't eye wateringly expensive.
I know a few people who've stayed there and said its a decent, clean and convenient hotel.
Downsides are its obviously a basic gaff, and round that area it can occasionally be a bit moody, and stink of rats piss.