another modern RPI alternative:
beaglebone black - about $10 more than the RPi. ( 8 times more IO, faster RAM as its DDR2, onboard emmc to boot without a SD card, more i2’s SPIs and UARTS, a ghz cpu, and it’s a ARM A8, which is better performer than both the A6 in the original RPi, nad the A7 in the RPi-V2. Oh, and it’s got accelerated video GPU, and two 200Mhz "PRU"s ( secondary spare processors, just for you ).
Ok, so the RPI-V2’s quad-core CPU is probably now going to make it’s CPU as fast as the BBB’s… but everything else is still worse. 
Also, if you want even sexier than the BBB, try:
Intel Edison: http://www.intel.com/content/www/us/en/do-it-yourself/edison.html ( maybe 3-5 times faster than the BBB, and double that again on the RPI ) an about $70ish? ( ie more than 5 times the RPI, and only twice the price )
or a super sexy Odroid ( they have a few):
Odroid-C1: completely compatible with the RPI ( it’s a drop-in replacement) , with a quad-core like the RPi-V2, but running at 1.5Ghz ( not the 900Mhz of the RPi-V2 ) , and it’s also got a true gigabit ethernet ( the RPI has 10/100 on the USB bus ) , so it still pants-s the new RPI on a bunch of specs … and STILL only $35 Bonus: the Ordoid-C1 can run Android , if you want. 
Odroid-U3: roughly same price as the BBB ( around $70-$80 ) , and 1.7Ghz quad-core, so it beats everything I’ve listed above on sheer CPU speed. Hint: it’s about as fast as 12 of the original RPI, or 4 of the new one. 
want the best “little computer” you can get…? try this beast: http://www.hardkernel.com/main/products/prdt_info.php?g_code=G140448267127 ( it’s got 8 cpu cores on it, and an OpenGL/OpenCL videocard, and it’s only about $180 bucks! )