Macerator or Water Pump - need recommendation

[nunyadamn]

I am looking for recommendations on a water pump or macerator pump. I have a 50 gallon bag that I will be able to fill in the back of my truck. I only want to be able to dump the grey tank. Can I go the cheaper route and get a water pump, or do I have to get a macerator pump? Can I get recommendations on what pump I would need? My original plan was to pump it up into the bag in the bed of my truck, then when I get where I can dump it, pump it back out of the bag. This would mean using a 12v pump. I am trying to stay cheap as I will probably only use this pump a couple of times a year at most. I don't want to spend a lot of cash and have the pump just sit around.