I outgrew the brazed on carbide tools in about 2 weeks. I researched tooling heavily for my G4003G and here's what I ended up getting...
Glanze Turning Set 1/2" shank - I found a number of people recommending this tool set, not sure what size shank tools your lathe takes but Grizzly has a smaller shank set as well. Imported from India.
http://www.grizzly.com/products/Glanze-Turning-Tool-Set-1-2/H5681 These all use the same insert, CCMT and CCGT its a pretty common insert and not overly expensive. CCMT for steel, CCGT for aluminum, brass, plastic, wood. The Kolroy CCGT carbide inserts are polished and razor sharp. I saw a recommendation for Kolroy brand inserts and purchased a box of 10 CCGT's from US Shop Tools in California. So far they work very nice. There are different sizes in CCMT/CCGT you want the 21.51 e.g. CCGT21.51
Glanze Parting Tool - you can spent a LOT more for this type of parting tool but I saw no reason to upgrade. For $99 you get the tool holder, two blades, 4 inserts I couldn't find a deal that came close to that anywhere. Grizzly shows some silver coating FAIL it was blued dark steel which suited me fine I don't like the silver coating. The 4 inserts that come with it are neutral and more suited for steel. It uses the common GTN3, GTR3, GTL3 (N-neutral, R-right, L-left) for the wider blade, I think the narrow blade is GT_2. I ordered a box of GTR3 Newcomer brand, US Shop Tools was out of the Dorian inserts. Specifically CI-218 C2 which are the C2 grade uncoated for aluminum and brass.
Boring Bars - I cheaped out here and went with the Grizzly set
http://www.grizzly.com/products/Carbide-Insert-CCMT-Boring-Bar-Set-3-pc-/T10438 this uses the same CCMT/CCGT inserts as the Glanze tooling above. I figure if I'm going to get into trouble and wipe out a tool its probably going to be boring so rather that blow big dollars on boring bars I'll practice with these. They seem perfectly fine quality wise. The strategy here was to try to limit the different types of inserts as they are expensive. So both my turning tools and boring bars use the same insert.
For threading I went with Carmex tool holders and laydown inserts. These were widely recommended in my research. I purchased these external and internal Carmex tool holders from US Shop Tools T-CMSER0625H16 $82.50, T-CMSIR0500M16B $105.42 then found them cheaper elsewhere (face palm) the internal is plumbed for through coolant, the non-coolant version is much cheaper. I went with these threading inserts for starters. There is a maddening volume of threading inserts, a bunch specific to a particular thread pitch, others like these below that can turn a range of threads, then there's like 3-4 different sizes these below are 16's there's also 11's and some others similar to the CCMT/CCGT inserts above coming in different sizes.
T-C16ERAG60K2 $11.43 (they sent me the wrong insert, should have been K2 uncoated it was coated)
T-C16IRAG60K2 $12.95 (they were out of stock)
T-C16ERAG60M2 $12.95
T-C16IRAG60M2 $12.95
Tooling FAIL to avoid
The Grizzly parting tool holder blows ass, I started with the HHS parting blade and their recommended tool holder, the parting blade is beveled top and bottom, the tool holder is flat and the blade won't lock in place properly :angryfire:
CHINA tool holders, about every other one is poorly made. Tapped crooked, loose height stud threads. I'm done buying any more and will go Dorian tool post and tool holders from here on out.