We've had good luck with RS Online in the past for that.
Thanks. RS doesn't really have much in the way of inexpensive rack cases though, starting at €35 (ex VAT) + €14 shipping.
How about https://www.servercase.co.uk/shop/server-cases/rackmount/ from the UK? I recently purchased one of those and the sales guy was very friendly and helpful.
Yep, have bought stuff from them in the past. Sales are also very helpful until you ask for spare parts, at which point they disappear down a hole. Anyway, these are built for server hardware, with all the requisite holes - which won't really work for me.
I should also note that if you skip the "inexpensive" option,
Audiophonics seems to have a fair selection of rack-mount cases. They do (erroneously) charge french VAT on orders to Norway, and they want €20 in shipping.