When I lived over there I paid 165 a month for parking in the bottom of my apartment building. In another apartment building in downtown, I paid 80 a month (A pre-covid special, that only went up to 135 or 145 I think? Cannot recall). Before that, I paid 204 a month at Saint Paul Plaza. I think the city posts the rates on their site. And the other private places tend to, too. Shop around, use Google maps to visualize the area, and you should find something.

I used to get Zipcars at 810 N Charles, for example: that has monthly parking iirc. It's a surface lot. I think the company is PMI, not sure.