Anyone who actually played with a $4 <4oz 1mil spaceblanket knows they suck, fall aparty, and are noisy as heck.

I have no interest in $150 WB bivy sacks that weigh in over a pound.

I've been using an $30 Adventure Medical Kit Thermal Bivvy at 9oz it has durability and quietness... finally beat it up to the point it has a few holes (4 uses). Now, I could just tape them and it will soldier on, but I was wondering if there is anything else out there:

<12oz
<$50
Durable
Quiet
But also has:
3/4 or full side zip/velcro (ever tried to get a patient into a 1/4 zip or no zip bag?) Full opening means it can convert for tarp or blanket use.
Gromets (not required, but a bonus)

I'd be interested in this as well. I haven't had much luck finding one though.

This is of interest to me as well!

I wanted to try this zipper mod but forgot about it,
I even picked up a couple of zippers.  Now I have to
figure out where I put them

I carry this with me as part of my get home kit when traveling for work. Has zippers and also a cinch cord.

1.7 lbs, but is a "real" sleeping bag:

https://www.amazon.com/dp/B000O1PKGE?tag=vglnk-c102-20

A little over the $50 mark but I think its exactly what the OP is looking for:

https://www.2gosystems.com/products/trifecta



-I have never used, or handled one, but was catching up on PM101 videos and came across it.  I thought it was very interesting.  I would probably pull the trigger on one if it was $30 or $40ish but I really don't have much use for one, nor can I justify adding one to my gear pile for the MSRP.  If its something you can actually put to use then I think might be worth it.

So, I have the V2 Trifecta thermal Bivvy.  I haven't really used it yet, but picked it up for some comparisons.  The good news is that it's pretty roomy, but I'm not sure how heavier Tyvek material will hold up over time.  I was surprised after looking this up and seeing the weight.  It's lighter than a ECWCS Gore-Tex bivy, but still pretty heavy for a "cheap" bivy.

The best I've found is Ti Goat's Ptarmigan bivy; a really solid design and top-end materials.  Weighing only 6.4 ounces is excellent and it's under $100.00.  For an ultralight and very functional bivy, this is my go-to.

ROCK6