As i'm at a point of increasing my actual 4 server count, how should I handle storing the OS of each server?

Problem: I have no money and I'm looking for a way to buy more servers without buying and taking care of new boot ssds.

The actual setup is that each server has their own 120/240gb ssd to boot from, and one of my servers is a NAS.

at first I thought of PXE persistent boot, but how would I assign each machine their own image is one of the problems..

I've found this post talking about Disk-less persistent PXE, but it's 5 years old, it talks about SAN booting, but most people I've seen in this sub are against fiber-channel protocol, probably there's a better way?

Without mentioning speed requirements (like a full-flash NAS or 10+gbit), Is it possible to add more servers, without purchasing a dedicated boot device for each one?