I live in norway so no walmart etc stores here 
Only 3 large retailers that do overall gadgets in walmart style but not walmart prices or selection sadly.
So its either small fans ment for bathroom exhausts at 15$ or the engine cooline fans i found at 30$.
Next is industrial gear at well not so fun pricing.
on the plus side i do have 12c or less outside 10months of the year, so semi-cold air to use.
downside is that since there is at most 1hot week of summer, there is no demand for diy A/C etc
Only 3 large retailers that do overall gadgets in walmart style but not walmart prices or selection sadly.
So its either small fans ment for bathroom exhausts at 15$ or the engine cooline fans i found at 30$.
Next is industrial gear at well not so fun pricing.
on the plus side i do have 12c or less outside 10months of the year, so semi-cold air to use.
downside is that since there is at most 1hot week of summer, there is no demand for diy A/C etc
You have an auto junkyard near you
Electric engine fans run on 12 volt,get a scrap one or 2.They move pretty good CFM & should be cheap 
They're waterproof,so you could mount them outside & since they're DC,you can reverse the rotation if needed
