There was a time when I used plastic bags - but I switched to strips of paper.
The strips of paper are about an inch wide - and I wrap them around leftovers that are all the same size and brand.
A small piece of tape will hold the band and is adjustable as I use the leftovers.
I write in pencil, on the paper, quantity, brand, and size
If I do not know the brand, I write either *nice* or *cheap* so I know at a glance
example:
13 Paper Source A7
or
15 cheap A6
I have drawers that are deep enough to have all of them standing up, and they are arranged by size.
I write the identifying info on the top edge that I can see when the drawer is open.
I bundle (by size) low quantity leftovers - with a gold elastic band (like you find on some gift boxes) they last longer than rubber bands
I have a gazillion stretchy bands from envelope jobs.
I think you can buy stretchy cord in spools at craft stores.
It's the same as tying with a ribbon - only stretchy.
If your drawers are shallow - and the envelopes will be stacked flat and slide around, the paper strips will hold them together nicely - and it should be easy to find what you need.
It is easy to slip out one envelope and if you only use one, you don't have to tighten the band. If you use a few - it is easy to just adjust the paper strip with the tape.
When I have more than 25 or 30 of one kind - I leave them in envelope boxes - that are on a shelf - labeled (on the outside) so I can see at a glance what's available.
On those, I add the color of the envelope so I don't have to get the box out and look.
Some of those boxes are the full 250 - others may have 2 or 3 different kinds -
as long as I take time to write the size, color and brand - it makes it easy to review what I have on hand
The paper bands are minimalist - and I can pack a lot more envelopes into a given space - and it's easy to grab what I'm after.