Cheap crap air pump could be modified to a water pump with a brake bleeder kit with water trap. Depending on the parts of the cylinder of course. I modified one a longer time ago, but well, it broke, due to the poor plastic. (Yes, a cheap one, we all start from somewhere.)
Most cheap pumps don't have a separate "valve pip", as in the cylinder is just attached to the hose and the pumping mechanism. Doesn't last long, modified or not.
Anyway, take your time, save some money (I know that can be hard, I'm in a monetary issue place right now) and get a
Bathmate one day.
Like in many better things at life, initial cost of something might be high, but in the end you might have spend the same amount of money or more on the less expensive item as you'd have to fix or replace it.
And remember to get your stuff from the Brotherhood for the maximum warranty!