Hmm, $300, I'm not sure you can buy 2 monitors for that,,, maybe 1. 
So either spend more or buy the headphones. 
Monitors are SO important.  I feel blessed that I don't have to worry about that, hopefully until I'm to old to care...
Listening to monitor in the store only helps if you know what to listen for. 
My NMS10 would be the last ones you would have picked because they sound boring to most people, no bottom end. But I and a lot of other folks could not get a mix that will play on every system right without them. I believe there are now the Yamaha HS80m that is the closest replacement, I'd like to try a pair. As you see, your budget needs a little more than doubling to get the good stuff. 

http://www.sweetwater.com/store/detail/HS80M

O.K., I just got back from the audition. I listened to JBL, Mackie, and Yamaha. All 5" drivers and 1" tweeters, bi-amped. The JBL's were open and sloppy, and even had what sounded like a little more high end biased. The Yamaha's were all high end and no bass. The Mackie's were: focused, tight, musical, articulate, almost seemed very flat compared to the other two. I am going with the Mackie's all the way. LOVE THEM! I am just a hack so this review means nothing...LOL. Later Brother's.