Update: See here where I use the Maple Mini under Arduino 1.5.8 to code hardware SPI to an SD Card, software SPI to a Nokia 5110 display, and I2C to scan for bus addresses.
While combing my favorite Arduino forum back in early September 2014, I came across an article discussing an inexpensive eBay offering for a Maple Mini Clone.
For those that do not know, Maple was one of the first 32-bit ARM processor boards that was designed and manufactured to work within the Arduino environment. Unfortunately, back in 2010, the engineers at Leaflabs were unable to utilize the official Arduino GUI, so they edited the open source Java code and built their own look-alike GUI. They also wrote an entire "core" to support the ARM.
For whatever reasons, history was not kind to the official Maple line and Leaflabs no longer sells the boards nor support the underlying libraries. The Chinese however have decided to spin numerous inexpensive ($4 - $15) boards. The new AliExpress website as well as eBay have these offerings. The Leaflabs website and forums are still online primarily for historical and support: http://leaflabs.com/
Currently, Roger Clark (see credits) hosts a ZIP on GitHub which can be installed in the user's Arduino "home" directory: that is, \Documents\Arduino\hardware\. Just build a new directory STM32 under \hardware\ for the expanded files. A significant amount of work has been completed and more work must be done; however, most of the examples now compile without error. The 40 page link on the Arduino Forum is a convoluted record of trial and error and ultimate successes and while a terse read, most of the installation issues and download issues are covered adequately. However, in my opinion, this is an "advanced project" and not suitable for newbies (noobies) primarily because there is no official Arduino support for the Chinese hardware or the Maple libraries changes that were required.
On my Windows 8.1 Professional development computer, I needed to place Windows into "test mode" to load the 32-bit unsigned communication drivers (serial and DFU.) On Windows 7, the reader can install unsigned drivers by following instructions from Microsoft: just Google for it. Other than the driver installation issues with unsigned drivers, everything else is standard. You will need to install Arduino 1.5.8 (or later) however as the newer Arduino environment is required to support multiple uC architectures. Once installed, you will be able to simply select the boards and communications from the Tools menu as you would any Arduino board.
My personal AliExpress experience
This is the link I utilized to order my 5 boards: http://www.aliexpress.com/store/812021
My experience was good - that is, I received the boards in 7 weeks utilizing the "free" shipping that was offered. When compared to eBay where shipping is "Air Express", this was about 2 weeks longer. Your experience may vary.
Please note that my links nor this article are intended to be an indorsement for any particular retailer or any mail-order entity. Many people report issues with such transactions up to and including not receiving the merchandise and not receiving a refund. Buyer beware.
Disclosure: I ordered 5 boards for $24 total. The $4 heading was rounded-down since $4.80 is less than $5. Yes, I know the official rounding rules, but $4 makes for a great title... poetic license.
I wish to remind the reader that while my personal experience with the Maple Mini clone has been positive, others may find that working through issues with non-working code or unfamiliar hardware no fun whatsoever! My boards are working well, SerialUSB is working under Windows 8.1 Professional but I have Windows in Test Mode: http://msdn.microsoft.com/en-us/library/windows/hardware/ff553484%28v=vs.85%29.aspx