for sports centers, you'll need to find and bring your own partner, and it costs something like 15-25chf for 45 mins. what you might like to do is join a club; you'll pay an annual fee up front, and pay a reduced rate each time you play, and if there's a squash evening, you just pay a flat fee for the whole evening, and you play with one another.
i go to the squash club at niederrohrdorf (
http://www.tcrohrdorferberg.ch/), which is 15-20 mins from baden by bus. annual fee of 300chf, and squash evenings on wed is free. let me know if u need more info.