May i ask which block/street your are staying? i am going to avoid that block... only superman can stop a falling object like an...... aircon.
Seriously, thrift on makan for a month and with money saved, have it installed by right the guy. If it goes wrong, you still got someone's head to hammer on.
As for such aircon, i was told it is not that energy efficient compared to a split unit system. the smaller it is, the harder it works. (YMMV though).
If its due to constraint of space/cash, and if its just for an occassional use, then, it makes sense to get a make shift solution.