One cutter for under $500 is a Roland Stika (several sizes)
It may not be big enough for your needs. Does not have optical eye which you might need. And not for heavy use.
www.rolanddga.com
I found a lot of information by going to signmaking message boards... signs101.com and signweb.com come to mind. Be warned that if you post there and you are not a signmaker, you may not get a warm welcome. So just search and read.
A few people here have posted about vinyl cutters (cutting plotters)
but it took some plowing through posts.
Also, Graphtec has come out with a hobby-level cutter.
http://craftrobo.com/
And information at sign supply stores (they have less expensive brands)
www.signwarehouse.com
or
www.signsupply.com