I understand exactly what you are looking for and have a solution that I came across that works with several different size batteries and cards.
I have two different ones that I use at this time one that I paid 10 cents for and one I paid $1.00 for that work great.
Flip phone camera cases!!! I have one that I now have on my camera strap, that has elastic on the sides and I keep 2 spare batteries and 2cards in it.
I have another that attaches sideways on my belt, you never know it is there and it will hold the same as above plus a shower cap and lens cloth.
The one with the elastic on the sides is slightly smaller and holds them tighter, but If I was going to choose just one I would use the one I use on my belt(and I keep it in my Backpack normally) as it is easier to get things out of it without the elastic.
Check your local garage sales, flea markets etc... with the influx of the new technology there are a lot of old phone cases out there for just a few pennies!!!
