Fixing the value of gear via the internet is so difficult to do that often when noobs ask that question, they get flamed. I am glad the folks here have not done that to you, and proud of them. That said, the estimates here will be wildly different, and so at least some of them wild inaccurate.
Two ways you can proceed:
1. Get an eBay account, and search for the items under "completed auctions." Be as specific as you can- An average of the ones you see will be fairly close- but could be inaccurate if there are only a few matching items. As suggested, you might want to limit your search to "down under," if that's where you are.
2. Bring it to a music store, ask how much they will pay you for it. that will be wholesale, so if you sell it on your own, double their quote. If you go to a pawn shop... well, forget about that. At least here in the USA, pawn brokers are crooks. They do stupid crap like "offering" about a tenth of what the gear is worth, then when you sell it, they put price tags on it at ABOVE retail/new prices.