$450 for the MX21LITEKIT. It is only 10 days old and I paid $550. I'll include shipping in the $450.
It has several good features like a QVGA touch screen and it boots Linux. I have 2.6 kernel form Microcross loaded on it. It comes with "support" from Microcross but their answer to all of my questions has been - buy a $10,000 support package and we'll see what we can do. The support that came with the MX21 kit seems to consist of a copy of their 2.6 kernel 'as is'.
Linux boot ROM is capable of NFS mounting the root volume. That makes it real easy to work on cross compiled apps from an x86 box. You can self host the compiler but it is a lot faster to cross compile with the NFS mount.
Another major feature is the integrated USB based JTAG. It only works under windows but you can use it to source debug interrupt handlers in the kernel if you want. Can't do that on any x86 box. You can also use it to reflash the boot ROM if you brick it. If you want Linux host support for the JTAG you need to buy a $250 hardware upgrade from Macgreigor.
Only big downside, MX21 does not have USB 2.0 support which was a requirement for our project. The Microcross written USB 1.0 driver for 2.6 only works for storage cards and no other USB device types. The host side of the USB OTG hardware is not supported at all. Philips has shipped an MX21 based VOIP phone running Linux. The phone is only shipping in the Netherlands and I don't know Dutch so I can't figure out where to download the source. Philips is good about making the source available, I just can't figure out the web site. I suspect there is a functional USB OTG driver in the download since their phone has working USB OTG. Freescale has a full OTG driver available for Linux 2.4.
The board has audio support and I have verified that the 2.6 ALSA drivers for it are functioning. The Ethernet is 10Mb only. I thought it was broken until I figured out that the switch I had it plugged into didn't support 10Mb - only 100Mb/1Gb. Kit comes with a power supply.
I have a copy of the Hantro MPEG4 encode/decode libraries. Royalties for those are included with the MX21 chip. The chip is capable of full duplex QVGA MPEG4 encode/decode. Adding a $6 camera to the Chumby would be cool but the socket for the connector has to be designed onto the Chumby board. MX21 supports most camera modules directly, there just need to be somewhere to plug them in. You need a 20 pin surface mount socket wired to the CSI pins. Then get a camera flex cable assembly. MX21LITEKIT does not have a camera socket on it.