Silent keyboard for programming / typing?

[Cromulent]

I currently have a Unicomp Model M and while it is probably the best keyboard I have ever used it is VERY loud so I was wondering if there was an alternative keyboard that was really nice to type on but was also silent? Full-size keyboard is essential.

 

[Cromulent]

Buckling spring switch is designed to be noisy.
If you're willing to do some work, here's one video with way to dampen its sound.
https://www.youtube.com/watch?v=iNFceYOJFVc

But really the easiest way would be keyboard, whose switch has been designed to avoid making unnecessary noise.
What kind budget you have?
Guess you wouldn't want standard membrane/rubber dome keyboard.

Budget of £100 to £150 I guess. I type all the time so cheaping out on a keyboard seems like a bad move. The noise has only just become a problem because I've moved into a shared house and it means I can't type late at night which is annoying.