Two track digital recorder (Fostex MR-8, Tascam DP-6, etc...) if you want independent tracking of the guitar and vocals.
If you don't care about that, get a stereo hand-held recorder like the TASCAM DR-5, or the Zoom H4-N.
I have a field kit that consists of my Mac Book, TASCAM US-800, two condenser mikes, and booms. I can pack all of that into a duffle bag. If you replace the Mac Book and audio interface with a two track digital recorder, you'll probably get the best mix of value and quality.
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