In the city at large, I see the cheapest apartment 750sq feet for 18k but you can be sure the whole building is falling down; cheapest empty lot $30k 2,500 sq feet (so maybe do-able if you can build up 2-3 stories, since you aren't actually allowed to build out to the edges of the lot).
Cheapest actual detached house in my 'inside the city, close to work and everything' neighborhood is an eye watering $440k and 1,500 sq feet, cheapest for sale apartment 700 sq ft $140k.
Most EXPENSIVE house in my neighborhood $2,250,000, and most expensive house listed in the whole city, add another zero to that price.