Let’s say 10-15. Based in the US.
For a collection of 10-15, you're probably better off making your own. Few screws, nuts and bolts, a Jigsaw/hacksaw, some sandpaper and timber and build your own would probably the most satisfactory.
If you purely want a cheap alternative, which won't display the bats, but store them upright, then look for a medium sized box of around 50cm x 50cm, cut some cardboard bat boxes in half, and fill the box with them. The bats will slot into the bat boxes, and won't get dented etc.
Something I whipped up last night as I had a big box lying around, and wanted to use it to store some bats. (Admittedly, I'd probably use thicker bits of wood which don't flex as much next time)
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All in all, depends if you want it to be practical, or aesthetic. You could even get something like a bookcase that is suitably large enough and modify it to hold bats.