Hey Mark
I am also new to the GT popping game and I'm yet test out my gear. I have found this forum and some others very useful at finding top quality gear at good prices.
I have set myself up with a Saltiga 6000GT and a custom built Calstar popping rod, both second hand but in great condition and both at a great price.
as for line i have gone with 80 and 100lb Tufline XP which is a solid performer, and won't break the budget. Ebay was really good for this, i saved a lot of money almost half price compared to some of the local tackle stores. just put it into the search on ebay.
Low to mid range poppers i have found are the halco Roosta's, River to Sea Dumbells, and the Nomad Cubera's. Also the Timberwolf gars are good quality for the price.
Motackle.com.au is good for all these at very good prices, and always keep an eye out for guys wanting to sell stuff second hand, you can almost always get a great price.
i have found several good sellers on ebay for terminal tackle, trebles and single hooks, split rings and swivels. most of the guys on here suggest no less than 300lb rating for terminal tackle.
As for leaders, I have got 170lb Fisherman Super Stealth for single leaders and blackmagic and Penn 10x for twisted leaders. 130lb and 150lb are pretty much what you'll need
these are very cheap of motackle or similar, also some of the gear on fishhead.com is very well priced. Jai poppers looks the goods
hope this helps
Cheers Anthony