Timely post. I've been struggling w/ the same situation, and just wandered around HomeDepot awhile until I found the parts. I looked for an actual storebought solution, but didn't find anything that can support 27" monitors.
I've been working from home for 15+ years, big laptop on a big lapdesk, in a recliner. Decadent, yes, but productive.
About 6 months ago, I built myself a standup workstation to force me off my big arse, and added a 27" monitor above my 18.5" laptop. Loved it: more screen, felt more awake, back felt much better (highly recommend the standup to anyone having weight/back/etc issues from sitting all day)
Then I started jogging on the treadmill 30-45min a day. For all its great benefits, working at the standup tired my legs before my jog, so I went back to the recliner, but missed the 2nd screen. So I took another spin around HomeDepot and grabbed some parts and built what I needed...though it took several iterations.
Hints: don't use cheap aluminum braces, the weight of the monitor torques it too much. I'm picking up a beefy steel brace today. Unless your stand will be attached to some other furniture, and be fairly short, use metal (1.5" conduit or similar), rather than wood for the poles. I used a wooden closet rod, and it definitely bends a bit. I've been able to compensate, but will probably upgrade to metal in future.
And as a base for the whole. thing, look for a hefty patio umbrella stand. I happened to have an old one lying around that does the trick, but it may need more weight.
This probably sounds like a lot more effort than you had in mind, but sometimes the best solution is homebrewed.