Instead of buying spray bottles, save plastic spray bottles from cleaning agents, wash thoroughly (especially the spray nozzle), and reuse for DIY/homemade cleaners, to spray your plants, etc.

I notice that some of the spray bottles for the cleaners I use like Greenworks are made of hardier plastic and spray nozzles than the spray bottles I see in/buy from stores. When they're empty, I clean these bottles out a couple of times with hot soapy water to get rid of any chemical residue, and repurpose them for something else, like homemade cleaners, fabric freshener, and to spray my plant babies.