I'm looking for a portable mixer that I can use in the field that runs on batteries and has phantom power for a shotgun microphone. Right now I'm using the mackie 402 but it needs a power adapter to run the phantom power and I'm unable to use it outdoors on a shoot if there isn't a power outlet anywhere. I'm looking for one in the $100-400 price range. What would you guys recommend?
Single channel? I (Of course) would suggest the Sound Devices MP-1 or MM-1. If you can find one used, it would be under $400. A new one of either is about $420~$475. Two AA batteries, phantom power, tons of gain, and specs to rival any boutique preamp on the market. the Shure FP-23 is the same as the MP-1. Sound Devices actually manufactured them. Here's one on ebay for a good price.
But you did say mixer... Our MixPre is cool, but it's pretty far outside your price range ($855 list price). Same preamp quality, 2 AA batteries, phantom power, etc. The Shure FP-24 is the same thing (Same as the FP-23 = MP-1. Made by Sound Devices. Same exact thing). Here's a FP-24 on ebay for a good price. I would definitely grill the seller about its condition, but don't be put off by the fact it looks beat up. All our mixers and preamps are tanks. They can look like sh*t and work beautifully.
The MM-1 and MP-1 have transformer balanced outputs, and the MM-1, MP-1, and MixPre have transformer balanced inputs.
That's my openly biased suggestion.