Hi, welcome to Chiang Mai.
I've been based in Chiang Mai for some 7 years now (and it's been better than '7 years in Tibet'!).
Over the years, I accumulated a number of apartments that I renovated and I've kept the ones that I like. You're most welcome to stay in one of them.
I'm confident and proud to say that most of my apartments are of higher quality than other units in the same buildings, because I've spent considerable effort and made more investments to make them nice, to design them well, so that they are livable and safe both for short term and for long term.
If you're looking for the cheapest places in town, I'm sorry I can't help you: you can find apartments from as cheap as 2,000 baht a month if you really like to live like a local. But if you're looking for a nice place and be comfortable and safe, I'm confident that I can offer you a unit that isn't expensive for the value you get.
In general, in Chiang Mai, what you pay is really what you get.
In principle, I'm more focused on longer term rentals (3 months up) but if a unit is available I don't mind short term (preferably from a month).
I'm not an agent so I do care about your experience and the quality of the units.
Some of my ex-tenants have become friends, and I do care more about having a nice tenant than "filling up my gaps'.