M's apartment is about the same price:
http://www.koratmap.com/en/hotels/apartments-long-stay/ms-apartments.htmlThere are several places downtown at about 200 baht, like Cathay hotel (near Yamo - but there is a lot of prostitution there) or closer to the city pillar. For 200 baht, you have a fan, a bathroom, it's normally an old hotel but if you don't need more, that's fine.
Another place is just beside Yamo, at the entrance of Pho Klang. It used to be a jail many many years ago. There is a tunnel, it's almost in front of the new OTOP place that I believe is not open yet. Really 200 meters from Yamo. A friend of mine stayed there about 2 years ago and If I remember, it was about 250 baht.
If you want to pay 500, the Siri Hotel, or San Sabai are pretty good.
Another one quite cheap is the doctor's guesthouse. That's behing Pailin square, the road behind CC or near the railway. Many backpackers go there, or at Cathay because they are (or used to be) in the lonely planet.