As long as you get a closed system, like the madela, you're fine buying gently used. The tubes, flanges, etc can be replaced.
I believe most insurances cover the cost of a new pump now. Check with your insurance and see.
I bought a madela pump in style advanced when I was expecting. I used it for a couple months while I was working after she was born. But when I was home I never used it. I had a madela hand pump that worked just as well. I wasn't pumping regularly, so it was all I needed. 4951