I can't let a topic like this pass by without mentioning commercial (often obsolete) FPGA-based products that are repurposed as development boards. They usually offer FPGAs with much higher capacity for rock bottom eBay prices.
Playing with these has been a fun hobby of mine and while I have a box full of 'real' development boards, I usually find myself going back to the Cisco board for my personal projects.
* Pano Logic G1 board: https://github.com/tomverbeure/panologic
* Pano Logic G2 board: https://github.com/tomverbeure/panologic-g2
* Colorlight 5A-75B: https://github.com/q3k/chubby75
* Cisco HWIC-3G-CDMA: https://github.com/tomverbeure/cisco-hwic-3g-cdma
Playing with these has been a fun hobby of mine and while I have a box full of 'real' development boards, I usually find myself going back to the Cisco board for my personal projects.