I was keen to pick up a router this weekend to pair with my DrayTek Vigor 130 and was after something cheap, in stock and compatible with OpenWrt. Most of the OpenWrt compatible routers start at around ~$120 and PB Tech only really had the TP Link range physically in stock.
After a fair amount of Googling I did however come across the Tenda N60 / N600. While its not explicitly compatible with OpenWrt it will run the Tomato firmwares. More specifically the AdvancedTomato and Tomato by Shibby firmwares.
The N60 is using the BCM47186B0 chipset with 8Mb of Flash and 64Mb of RAM and all ethernet ports of gigabit making it very similar in specs to the Linksys E3200 which are still $100+ on TradeMe and known to run OpenWrt*.
One caveat, I haven't tested the WiFi as I am using an Unifi AP instead, so the quality of the WiFi was of zero interest to me during my research.
For anyone after a cheap router to flash with custom firmware they don't come much cheaper than this.
*I suspect the lack of OpenWrt support is simply due to the developers not having access to a unit and not a hardware compatibility issue.