I'm on a budget too, but I do keep one 6000 BTU window air conditioner running from late April to late September. It doesn't keep the other end of the 1200 sq foot house cool, but it keeps the humidity down some. It is only set to 78 F on the faceplate thermostat.
I tried living without air conditioning in Houston when I graduated from college into the post Viet Nam War recession. The interior walls midewed in my stucco house! So no more iron man, for me. The room air is costing me about $60 a month June -August, less in spring and fall with the cool spells.
My Steinway console gets one sticky key in the dry of winter. It seems okay with summer. It peaks at about 80-84 deg in the piano room. I have to use a fan to keep from sweating on vigorous pieces. I don't shut the A/C off when I stay out at my country trailer in the summer, but I do turn the thermostat up a little.
The trailer is up on a ridge between the Ohio & White river drainages. No A/C, no running water, no heat, but it is windier up there and there is much less ozone. Only 15 miles from the Ohio river, but such a different climate up there.