My bad, I didn't realize you were only looking to spend $40.
Although that's definitely a tough price to meet, you might be able to find a gently used TKL for that amount. I'm not sure if they make a TKL, but Rosewill (Newegg's house brand) typically offer the lowest priced peripherals, and they're usually well reviewed.
BTW, keyboards built with Cherry MX switches (the majority of name brand gaming keyboards) are more expensive, but other switches are supposedly just as good.
Henk