Hi guys.
I've gotten brilliant help here before, so I hope someone will have some input on this little challenge.
My band has it's own little festival every year. Actually, it's not that small anymore, with 10-15 bands playing this year - but the venue is small.
We're calling it a Nano-festival, as it's only room for about 80 people in the concrete backyard where it's held.
We use a small PA-system, and run the vocals and the keyboard through it.
The rest of the sound is bare amplifiers and drum-set. The venue is so small there is no need for anything else, and the sound is actually surprisingly good, to be played incapsulated in concrete.
The first two years I taped it with a stereomicrophone in the center of the backyard to my Edirol R-09HR.

You can see the microphone at the left edge of the stairs, beneath a camera covered in plastic.
The set-up on stage looks like this:

The microphone in the back did a great job picking up the amplifiers and the drums, but the vocal was too easily drowned in that recording
What really saved my recording was a camera I had placed on the side of the stage, which picked up on the monitor-mix. So I used that audiotrack, and mixed it with the track on the Edirol.
What I want to do this year is to tap the mixer and get the vocals - and use a microphone in the back to get the rest of the instruments as last year.
Are there any great ideas on how I can get this to work?
I'm willing to flesh out up to a 100$ on a mixer of sorts, and I've had this recommended for me;
http://www.roland.com/products/en/M-10MX/I've also had someone suggest taping the instruments separately, and tapping the mixer through this to my computer;
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250803287568&ssPageName=STRK:MEWAX:IT#ht_3865wt_905But I really want to hear what some of you guys think, as the ones suggesting are smart soundpeople by all means, but none of them do any field recordings.... so it's a lot of theory and not really any practical experience.