ZBasic Forum

It's nice to see a US supplier but, the $4 WeMos D1 mini V2 includes a USB-Serial adapter, 5V & 3V3 regulators and lends itself to expansion using either their shields or those you design yourself. (I'm awaiting delivery of some mini PCBs I designed.)

http://www.aliexpress.com/store/product ... 01036.html

BTW, ITead Studio is a good (and extremely inexpensive) source for PCBs.
https://www.itead.cc/open-pcb.html

Of course, shipping from China is very slow if you choose the inexpensive shipping options. (My boards, mentioned above, took 23 days for free shipping.)

This looks even more promising although it's still a few months shy of production for the latest versions.
https://www.indiegogo.com/projects/omeg ... -for-iot#/

It appears well planned - it has the computing power of the Raspberry Pi plus built-in WiFi with a footprint marginally larger than the WeMos D1 mini (but needing more auxilliary boards). It boots a version of OpenWRT out-of-the-box. And there are numerous expansion modules that span very wide fields of interest. That it comes from a company called Onion is slightly worrisome.
https://wiki.onion.io/Home

There's a $5 (Omega2) version with limited memory and a $9 (Omega2 Plus) version with more memory and a microSD slot. Both also need a dock for power and communication. You can preorder through IndieGoGo.
https://www.indiegogo.com/projects/omeg ... -for-iot#/

And, I just came across the $10 Orange Pi which has an enormous amount of onboard memory. It's unclear what else it may require.
http://www.computerworld.com/article/31 ... board.html

Espressif says...

ESP8285 is the ESP8266 chip embedded with 1 MByte flash memory specially designed for wearable devices.

Itead has a $2.10 ESP8285 board.
https://www.itead.cc/psf-b85.html
There's USA supplier of a development board on Tindie.
https://www.tindie.com/products/onehors ... ent-board/