Amazon has the Karaoke USA Portable System (Black, GF839) for $56 with free shipping. Features 35W peak digital power amplifier (25W RMS), record voice and music mix and instant playback, 300 MP3G songs.
Has good Amazon Reviews.
eBay has the Open-Box Sony WiFi Blu-ray Disc Player. (BDP-BX370) for $40 with free shipping. List price: $100. Include 1080p video playback, built-in WiFi, built-in streaming apps (Netflix, Hulu Plus, Pandora, etc.), HDMI, and USB.