What camera would work better?

I go to concerts often(small venues so far) and take quite a lot of photos of basically anything that's pretty interesting but I don't have a good quality camera and using I can't use an iphone because I don't have one I usually end up taking on that isn't mine to snap a quick photo. I've also been wanting to get into photography for quite some time for future purposes for family and friend meet ups.
I've been on craigslist for a camera due to lower price then in store. I've found a d3000 Nikon Camera, Sony a230 DSLR, Canon EOS Rebek S II and a Canon EOS 20D.
If anyone could suggest one that is better then the ones listed. Possibly under $400 if possible.

Canon