Welcome Nikki,
Decent second hand rims can be found in the for sale section on this forum at reasonable prices. There seems to be a lot less threads on here these days so check gumtree or wreckers too.
Check out bracing.com.au for suspension parts as their products are high quality at decent prices.
Best initial bang for buck mods are replace intake w/pod style and shielding (Apexi work great), then 3-inch turbo back exhaust system (blitz not bad if you like cannon tips).
Splitfire Coilpacks are decent though similar ones can be had cheap.
Nengun are recommended for genuine jap brand new parts and justjap are the local equivalent.
Enjoy modding and get ready to burn a massive hole in your pockets!