1) start up costs can be quite costly but maintenance and up keep are low in comparison. save up.
2) P90's aren't cheap. I've seen them go for 400$ at the cheapest so far. as for stores nobody carries them. your best bet is to check the classifieds when you get verified
"You know what the chain of command is? It's the chain I go get and beat you with 'til ya understand who's in ruttin' command here."