Um I dont "store" my TFs as I too have a dedicated room for them. But I can suggest that since youve got them ziplocked individually ( good way to keep the dust off as well) try to get some stackable plastic boxes. these are available in various sizes ( depending on how many liters you like) as these wont get squished when stacked together and offer better protection for your TFs while in storage than Cardboard boxes will ever give. They come in various shapes as well - flat ( for under the bed storage) slim for sides of cabinets, or just plain bulky for whatever but at least they're stackable saves space, durable and offers good protection. if you wanna keep your Tfs from tumbling around in the boxes just buy some bubble wrap and "layer" it like a lasagna. TFs bubble wrap, TFs, bubble wrap til theyre snug and secure. Hope this helps as this is what I did when I had to transport my TFs to the new house when I moved out of my aunts place. These are usually abvailable in any Reject Shops, Dollar shops
Edit and Addit: I had about 400+ TFs when I had to transport them. They all fit snugly ( in vehicle/alt mode) in 3, 94liter plastic boxes. stacked on top of each other. NOw I use these to store my unused Lego bricks.
Wanted AM partner Vanguard, Myclones Dirge, G1 Victory Leo, e-hobby Dark scream ( the black version), e-hobby Magnificus
Parts- AM partner Basher-side guns, G1 Actionmaster Elite Windmill's blades[I][B]