Spray bottles are available at Wal-Mart, Home Depot, Lowes, and Probably Target as well. They can usually be found it the garden or cleaning supplies department. They should not cost more than a Dollar. I bought a pack of 5 for about $3-$4 they have lots of uses i.e. BBQ, Flare-ups when grilling, misting house plants, cleaning supplies ( they work better than the ones that cleaning stuff come in plus you can by large bottles & dispense into spray bottles.
I strongly recommend that the bottles be labeled both for safety & hygiene I label mine “Water Only†“BBQâ€, “Plant Food†use whatever works for you.