I've been taping almost every show that I've gone to for the past nine months now. The only times I haven't were when I thought security would be way too tight.
I've just been using a Sony MZR-700 and a $70 mic for recording. Grand total was around $270. I've recorded 23 shows since then, so that's not too bad. Another 250 shows and I'll be down to $2 per show, counting the media.
I suppose that probably won't be happening for a while.
It's remarkably easy to get the recorder into shows. I've only been to one show with metal detector wands, and I just went back to my car with the recorder and went to the show without it.
Quality of the recordings has ranged from good to excellent. I've been really happy with the whole setup so far. I know that a lot of people spend way more money on recording equipment, battery boxes, etc. but this is perfect for my needs. I just like to be able to listen to shows again at my leisure.
I'm not sure what your budget is, but I'm sure you could get less expensive equipment and still be happy with the sound.