If you want a razor that can survive a drop, then you’ll want to stay away from from the previous two recommendations. They are also chrome plated zamac and won’t fare better than what you’ve tried.

You’re right that stainless steel razors tend to lean expensive. The closest to your budget I can think of is the mühle Rocca , which is a great value IMO, but still pricey.

Brass is another great choice that’s much more durable than chrome plated zamac. You can get brass razors with it without chrome plating and it’s mainly a question of esthetics: chrome plating is shiny (but can chip), unplated brass develops a patina if it isn’t polished which some people like, others don’t.

In brass, you can choose between myriad vintage Gillette Tech razors on eBay (cheap, great razors that will outlive you) or modern brass razors like Fatip which will likewise outlive you and cost you under 20£.

I personally enjoy the Lo Storto Fatip a lot.

Some razors are marketed as “tripple chromed”. Are they any better?

No. The only thing that matters is under the chrome plating. Even if you never drop your razor, at some point you’ll wear through the playing at the threads of the screw post, and the underlying metal will be exposed. If it’s brass, nothing happens. If it’s zamac (potmetal), it’ll corrode and break quickly.