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.

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.