It's not the $4 it 's the taste the pink stuff leaves. Guess if you use the pink you buy bottle water to drink which is going to cost more than $4. I use full air pressure (100+) and do not have all the valves closed for for very long which gives a good rush of air when you do open one.
I drain the two air tanks on my MH and never get any water or oil... It's called a air dryer. If you use a little portable there's no oil or water either but it's hard to get enough volume with one if you have a hot water bypass.
