ISO Office Rental for 1 Person (therapist)

I'm looking for a private office for myself to see therapy clients in the downtown or Avenues area. Just one room big enough for a couch and a couple of chairs. I am only finding really tacky looking coworking spaces and have seen a few nicer offices in older buildings downtown, but to no avail.

My budget is up to $500-600/month.

I don't like coworking spaces and they just feel odd as therapy offices to me.

I can do a 12 month lease, and pay it all upfront in cash, and do financials/credit check no problem. Just really looking to move into fully private practice and desperately need a space that fits a few criteria (quiet, not super new weird looking construction, i love old houses and 1910s buildings)

Anyone have any suggestions?