Sparkfun has the Netduino Plus 2 on sale for $50 (+shipping) and has a coupon code RETROSPARK for $10 off $40. Sale runs until 11:59 p.m. MT on 8/17/14.
https://www.sparkfun.../products/11608
Get one while they're cheap!
Edit:
Here's a full list of what they have on sale right now: https://www.sparkfun.com/news/1564
Also, the RETROSPARK code is good for $10 off any order of $40 or more, it is not NP2 specific.