your paying for 2 hours gas...
just go to your LFS or buy a RO/Di unit online....
dont forget......i would sell my 300$ RO/DI, for 30$ to... but thats after my TDS reading was 20.0....ro or ro/di units have filters in each chamber... if your buying a used one, its a sure bet the filters are totally used up, so when you get it, you will just have to buy new filters.
bite the bullet, get a new ro/do unit...