I have a Q-See system that has worked great so far. You will need to run wires though. One thing about a wireless system most people forget is they have to be powered. How many outlets do you have in your attic. I had one. So you will have to run some kind of wire whether you use wired or wireless...
I’m a caretaker for this house. I am cool with running wires. I earned an ass in Electronics in a previous life. The world has passed me by (kind of) technology wise, but I’m not completely befuddled. Just need a push in the right direction.