Thats 30 million times ten times one thousand. Thats 300 billion dollars. That is ten times the cost for the war in Iraq back in 2001 and 2002 (both years). How on earth do you think the US could pay that considering that it has a deep deficit in the first place?
And in any case, one purpose is to be a replacement for the current piecemeal programs we have, which aren't cheap to begin with. Food stamps + Section 8 + EITC currently costs about $150 billion per year, plus some additional amount in bureaucracy and litigation due to complex rules, plus some additional economic damage caused by market distortion due to the fact that food stamps + section 8 aren't normal cash (EITC is better for that). That leaves maybe $100-150b, some of which is probably also redundant with existing welfare programs (I just picked three big ones), or about 3-4% of the federal budget.
If you want to keep it budget-neutral, how about an across-the-board 3-4% cut to all other budget categories in return? Or, we could just, as you point out, remove the temporary "overseas contingency operations" (Iraq/Afghanistan wars) supplement to the regular DoD budget, which is $125b in 2012, returning the DoD to its baseline budget. If I had a line-item veto pen I could pretty easily come up with another few hundred billion in savings if you'd like (cut agriculture subsidies, cut Medicare Part D, transition TSA/air-traffic-control to being fully user-fee-funded, do another round of domestic military-base closures through a BRAC-like process, etc., etc.). :)
And it's not like that $300 billion just disappears into a black hole. Because poor people need it to live they are spending it immediately, which multiplies out across the economy, certainly more so than a war does. And I'm not even counting the human life cost of war. So yes, just giving people $10K a year isn't that bad considering what we have done.
I just love the thinking though: "we've spent all this money to kill people for no reason and now you expect us to feed Americans?!?!"