I'm looking to replace both rather worn knobs with the OEM standard rubber or aftermarket black aluminium anodised type.... any suggestions where I could get the latter?

Try Powerfull UK

http://www.powerfuluk.com/vehicles/range-r...erior.html

Andrew My first RRS HSE Purchased June 2016
Java Black 2.7
Date of first registration 22 February 2008
Cousin of the King of Stamford Bridge R.I.P. Ossie

Thx.
I've seen these, not too keen on the alloy tho. Wanted something more suiting the car... guess these could be sprayed black.
I may do that as a last resort

I had same issue on my radio the buttons had a grey and well used look about them. I just could not part with £40 for a pair of knobs. I used a tin of peel coat black rubber spray (Halfords) its finish is matt and gives a good restore look to them. I had some pics of before and after( if I can find them I will post up), well worth a go . And the best bit is if you don't like you can just peel it off. Comes in various colours but black matt suits the factory look.