ebay was a bit rubbish
I've started looking at TV ones but I've not found any that have adjustable height. They're mostly like this.
( Captain V, Wed 12 Aug 2009, 14:28, 2 replies, latest was 16 years ago)

Have you already bought this?
Because in the "Customers Who Bought This Item Also Bought" section there is a pair of shoes that look like they'd fit you.
( crackhouseceilidhband Fuck off back to Mumsnet, Wed 12 Aug 2009, 14:30, Reply)

Hmmm...
Unless you can get two of them and mount them on something that allows adjustable height pivoting...
( Cawl, Wed 12 Aug 2009, 14:30, Reply)

What about this?
www.amazon.co.uk/Philex-Tilt-Swivel-Wall-Bracket/dp/B000HDASSO/ref=pd_sim_k_h_b_cs_16
( Cawl, Wed 12 Aug 2009, 14:31, Reply)

No vertial movement
I've found these which are much better price wise but I'd rather the height adjustment were incorporated into the arm. Maybe there aren't such things at the sorts of prices I'm looking for.
( Captain V, Wed 12 Aug 2009, 14:34, Reply)

the ones I found like what you are looking for were $259
I think they are just expensive things. I hate it when that happens
( Vipros. clever got me this far, then tricky got me in, Wed 12 Aug 2009, 14:34, Reply)

I think you're right
Maybe the ones mounted on a pole will have to do.
( Captain V, Wed 12 Aug 2009, 14:37, Reply)

Spitroast time?
ALREADY?
( Cawl, Wed 12 Aug 2009, 14:39, Reply)

in which case
they can be tilted side to side and forward and backward on their own mechanisms and you may as well just stick them on an stack of (height-adjustable) Yellow Pages.
( crackhouseceilidhband Fuck off back to Mumsnet, Wed 12 Aug 2009, 14:39, Reply)

He's using all the Yellow Pages
On his desk chair already.
( Cawl, Wed 12 Aug 2009, 14:41, Reply)

Ha! Poor catface.
But seriously, don't prompt him to look for a new chair.
( crackhouseceilidhband Fuck off back to Mumsnet, Wed 12 Aug 2009, 14:44, Reply)

I can't do that online
I need to sit in them to know whether or not they're comfortable!
( Captain V, Wed 12 Aug 2009, 14:45, Reply)

Just get a booster-seat.
Or steal a high-chair from a restaurant.
( Cawl, Wed 12 Aug 2009, 14:51, Reply)

I can't rotate them sideways though
For extra vertical screen space.
( Captain V, Wed 12 Aug 2009, 14:43, Reply)

tilt your head

( Vipros. clever got me this far, then tricky got me in, Wed 12 Aug 2009, 14:44, Reply)