Dmitry (omgfire), one of my awesome readers, compiled a great tabular list of Linux friendly boards and products that sells for less than $300 US (usually less than $200). This list includes technical details such as the processor, GPU, memory, NAND flash, connectivity, ports, supported Linux distributions… as well as availability and pricing information.
There are currently 39 Linux devices in total. The vast majority are ARM based boards, but he also included 2 x86 products by VIA, but those are relatively pricey ($265 and up).
Here’s a summary list with SoCs used, links to blog posts and product pages (if available), as well as price information.