...My budget isn't crazy as I'm looking to shop around and I don't mind if it's used as long as it isn't abused. I would think of a budget in the $500-700 range. As far as mic stands, cables, and mics we already have that stuff and it wasn't that expensive if you know how to shop.
You might consider having you & the drummer each contribute parts of a new PA. This can help stretch your budget a little farther. For example, it never hurts to own a pair of powered 2-way speakers. There are all kinds of things you can use them for beyond just this one band & you'll have lots of flexibility. There's no telling what other groups you might want to get involved with, now or in the future, & your value as a potential member goes up of you have "common" gear to use.
I have a general rule of thumb: "Everything costs $500". It's easy to drop $500 on a decent mixer. A pair of speakers? $500. Power amp(s) to drive the speakers? $500 (if you get powered speakers, consider that as
both power amp & speakers, for around $1000. Effects? $500. Mics.? $500, stands & cables? $500. I also like to toss in another item that I call "Misc.", for all the misc. stuff that doesn't quite fit in the other categories such as racks, cases, speaker poles, cart, overruns in other areas, or whatever for another $500.
So, for a system with 2 mains, 2 monitors, mixer, effects, mics, stands, cables, etc. my rough math totals up $4500, which is probably not far off the mark for a club-sized PA for a rock & roll band. I know several people who have spent a bit more than that for something similar, mostly buying new.
Like you say, shop around & you can often find better deals, especially if you look for a used analog mixer, analog effects, unpowered speakers, & separate power amps - the kind of things that a lot of people are replacing with digital/powered units these days. What you're likely to get for $500-700 may not be what you want. However, if you go in expecting to shell out $4500, & you can get it done for $3000, you'll probably feel a lot better about the purchase.
It can help to build in stages. Try to identify some details about what you want to end up with, giving strong consideration to flexibility & expansion capability in the future. Start with a basic, bare minimum to get by for now, & add more stuff as you can.