Boston is the most expensive Nationals I've attended. They have such a huge fan base that they aren't offering weekend packages and said that right from the start.
I went to Greensboro in 2011 and really enjoyed it. The main arena and secondary arena are in the same complex and both offered food. Food wasn't cheap but it wasn't scarily expensive either. I had friends who bought the cheapest all event tickets and were able to move down until the Ladies Final. All event ticket gets you a practice pass too - so that is something you might be interested in.
I went to Greensboro in 2011 and really enjoyed it. The main arena and secondary arena are in the same complex and both offered food. Food wasn't cheap but it wasn't scarily expensive either. I had friends who bought the cheapest all event tickets and were able to move down until the Ladies Final. All event ticket gets you a practice pass too - so that is something you might be interested in.
A little OT, but although I can't quite bring myself to commit to the time and money for the All-Event Package, the Championship Weekend packages for Greensboro 2015 are looking very nice! They are already doing at least a fair bit of promoting with email blasts and other social media.