Recommended board for prototyping? Advice needed!

Howdy,

I’m starting a new project and I’m looking for a board that has these capabilities (either onboard or thru shields/modules) to build a prototype:
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Low power
Function as a Usb client
Function as a Usb host
Non-volatile reliable storage
Reliable real time clock with battery backup
Wifi - 802.11 g/n (speed does not really matter, only compatibility) capable of ad-hoc or infrastructure connection, with support for HTTP, SSL and NTP.
A buzzer or other simple sound device capable of emitting beeps
Enough pins to use a thermal printer, a fingerprint sensor and a 20x4 RGB LCD display (Mini Thermal Receipt Printer : ID 597 : $49.95 : Adafruit Industries, Unique & fun DIY electronics and kits, Fingerprint sensor : ID 751 : $49.95 : Adafruit Industries, Unique & fun DIY electronics and kits and RGB backlight positive LCD 20x4 + extras [black on RGB] : ID 499 : $24.95 : Adafruit Industries, Unique & fun DIY electronics and kits respectivelly)
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Having the option to add battery backup power (lipo or similar with charger) would be a bonus.

The project is quite simple in terms of the software, there is no graphics (the lcd doesn’t count, right?), no audio, no gps, no servo control, the wifi will be enabled only long enough to POST some data to a couple of Web APIs and the entire board will mostly sleep all day long, only waking to read a fingerprint and print a receipt - in both cases, serial devices.

I was considering the Cobra II with wifi, since it seems to have everything in one place, making prototyping easier, but the price is killing me.

Would it be possible to use a Cerbuino or Cerb40? What would you guys/gals recommend me?

The WiFi means you’re probably looking at G120. You’ll need to be more specific on the “low power” requirement, though, as “low power” and “WiFi” don’t usually go together.

A g120hdr + wifi is about the price of the cobra II

Low power in the sense that it must be able to run on a Polymer Lithium Ion Battery - 3.7V / 2000mAh in the event of power failure. As for the wifi sucking power, I’m not really worried as it won’t run continuously, only in short bursts.

You think the Wifi won’t run, but honestly it will consume power all the time. It may not be using much, if your code can disconnect from the wifi AP it’s connected to etc and go into a low power mode, but that’s not likely to be a common scenario others will have tested, so you might want to validate this.

Sure, I’m aware that I’ll have to test things out and validate all that, but that’s what a prototype is for =D