Welcome to EAB
If you want to get hold of an Amiga, then Ebay is your friend here... you'll find plenty on there. Try and get hold of an A1200 if you can, preferably with a hard drive and some sort of memory expansion as this will probably be your best bet. Also you could try the Marketplace sub-forum here on EAB.
As for trackers, I'm no expert on the subject but you could always try Aminet for starters... however there are plenty of people on here who are far more knowledgeable on this subject then I am