get an old tape recorder and get someone to walk around the room and find a point where everything sounds nicely mixed. place the tape recorder's mic' at the position of the persons head and facing in the direction they were facing.
The way sound records to tape offers some natural compression which can sound quite nice and it's very low budget.
record the line out from the tape player straight into windows sound recorder(making sure to set levels to get maximum volume without clipping)
That's about the lowest budget recording I can think of.
edit:
looking at your gear list...
how many channels is your pa?
plug the line out's from your amps into the line in's for the pa channels.
put your vox mic straight into the pa.
get another 3 mics, put one inside the hole of the bass drum,
one on the snare
and another one facing the kit from a small distance.
im assuming you have an 8 channel PA
1 vox
2 guitar
3 guitar
4 bass
5 drums kick
6 drums snare
7 drums room
8 - whatever else
you can then hook your line out to your computer for a mono recording of the mix (once it is balanced, which may take some trial and error)
Sometimes I like to use words out of contents