Mesh hip belt pouch

I'm getting a new UL pack soon (haven't yet decided which) but none of the ones Im looking at come with a hip belt pocket standard. I have not tried it yet, but I am planning on sewing on a granite gear compression sack pouch (the stuff sack for the stuff sack) it seems large enough to hold plenty of snacks, etc. and will be easy to attach.

You should take a look at Zimmerbuilt.com in the accessory page. He makes some really nice add on pockets for your hip belt and shoulder strap. I have one for my belt and I absolutely love it. It's much easier to open and close than the built in pockets on most packs. There are other places that make these too, but I only have experience with the Zimmerbuilt ones.

On my Gossamer Gear Miniposa – owned before they came out with their own add-on hip pockets – I bought two Eagle Creek size XS zipper pouches. They have a tiny webbing loop on each end, one of which has a huge plastic clip. I sawed the clip off, ran paracord through each of the loops, secured each with a cord lock, slipped them over the hip belt, and cinched the cord locks tight enough they didn't slip over the hipbelt buckles, but not so tight they bent the hip belt webbing. Works like a charm, sorry I don't have the weight at my fingertips. These sacks do have a coating inside so they're not 100% mesh, but you can poke holes in the bottom if you need drain holes, and you can see inside of them from the outside.

chris, i've an item– essentially what you described– that might qualify.
it's actually the stuff sack to my montane featherlight jacket. i NEVER use it, it's literally sitting in my gear box. yours if you wants. as for size, you could likely fit some small items in it– lip balm, a pair of lightweight liner gloves, maybe a small-sized snack. toggle closure, velcro attachment and mesh for breathability. need a pic? lt