I'm guessing seats towards the back on the pavillion will be around $80. I usually only do lawn seats at Merriweather so that's only an educated guess.
In regards to selling out, I honestly have no idea. I can't see the Baltimore area drawing a huge amount of fans, but since there is no D.C. show, this is essentially a D.C. and Baltimore show. I would expect the lawn to possibly not sell out at all. Merriweather holds 10,000+ (I think). He sold out venues twice that size in Europe, but I doubt that success to translate stateside.
Looks like I'm going to have to bring my laptop to class tomorrow to get tickets. This is also going to be my first time ever going to a show alone lol.