Why don't NASA use kickstarter? If the govt. doesn't want to fund it, let the people do it directly. $5 could get you like access to a little mini-site with tons of info on the mission and some exclusive stuff, like maybe a higher res stream and stuff. $20 could get you a couple stickers posted out, $50 could get you a shirt, $500 could get you like a little jar with 5g of mars dirt or something and $5000 could get you access to a party with the dudes who're part of the launch.
It'd also make it international - i bet a couple hundred thousand people from other countries would give some money, and then maybe we could get the future of the human race back on fucking track.
Although personally, i'd bury the 'the waste will be dehydrated, so the wastewater can be recycled for drinking.' detail away from the public, because seriously you guys, that's so bad i will fucking build my own little space rocket to send them a couple jugs of water. Hell, let them borrow some from the ISS and we'll just resupply the ISS later. But for gods sake, only recycle water from the piss. At least the piss looks like a liquid, and doesn't even taste bad if you have diabeetus.
I cannot envision a lack of Delta-v sufficient enough to make shitwater a legitimate option.