In general the stipend is $1200 but those participants who elect to not incur housing costs will receive a stipend of $600. Here's the official NEH policy about this:
Stipend provisions: Only those participants who incur housing costs in a residential workshop week will receive a stipend of $1200. All commuting participants who incur no housing costs, regardless of workshop type, will receive a stipend of $600.
From the stipend some costs will be deducted such as workshop hotel costs (for those who stay at the workshop hotel), meals, and tour fees. Participants must pay for transportation to the workshop in advance of receiving the stipend. Generally participants outside of North Carolina, Virginia and South Carolina fly into RDU, but some drive or take Amtrak. Except in rare instances where a participate has traveled from outside of the continental United States the $1200 stipend covers all costs : hotel, meal, round trip airfare/other transportation expenses to the Workshop, tour fees and a few group meals when touring sites or working at the hotel.