I have several Wendt X4 4-Channel Portable ENG Field Mixers. These are used but in good working condition. Here is a description from the manufacturer:

The Wendt X4 is a portable, compact 4-channel field mixer designed for audio mixing for film, documentaries, ENG or virtually any application requiring a portable mixer. The mixer features 4 XLR balanced microphone inputs with individually switched phantom power allowing an assortment of dynamic and condenser microphones to be used simultaneously. Each input features a rotary level control and the master level provides global level control over all inputs. In addition switchable gain / attenuation on every input provides 10dB, 20dB and 0dB of level gain for dynamic or condenser microphones. 

The output section features stereo XLR balanced outputs and a stereo 3.5mm microphone level output jack for feeding signal to camcorders or smaller portable recorders. The balanced XLR outputs are switchable between mic or line level signal. A limiter switch is also located at the output section. The limiter minimizes transient peaks and reduces distortion caused by signal overload. The X4 is powered with 8-AA Alkaline batteries for up to 15 hours and a 2.1mm center pin jack allows the mixer to be powered with an external 9-18VDC source. A multi-pin accessory connector allows multiple X4s to operate ganged or can be used for monitor returns or external power.