I've been staying out of threads a bit lately because of the fact that for whatever reason lately, I've been receiving flack for speaking up. But to address a couple of things.
1) Getting an "eBay kit" only to replace about 90% makes no sense at all, nor is trying to get an older eBay turbo and "put better internals in it".. What people forget is that for most of these kits don't fit their own equipment well, much less be able to be transferred to anything else.
Now, for a good "kit" example, the Go-Autowerks kit is not a bad place to start, but I will admit that the "street kit" does limit turbocharger options for future use. I've always recommended the "tuner" kit as a start off kit , because that way you can substitute turbochargers, wastegates, etc, if needed.
2) ARP headstuds. . Ya know, maybe its the Geritol talking here, but in the 16 years I've been turbocharging B-series Hondas that are bone stock, for power levels of 250whp-400whp, I've never had to put in ARP headstuds "for safety". If I had to do that, that means that the engine itself or other components are also suspect; in essence, that the car is mechanically unsound in some way, and that the owner needs to seriously get the engine in tip top shape before even attempting to turbocharge. For lower HP goals like I described above, a set of headstuds thrown in one at a time is a bandaid for other issues in the meantime to rear their ugly heads. Make sure the car is mechanically sound first. Compression and leakdown tests, change out of filters, fluids and checking of other areas is worth its weight in gold over some ARP headstuds.. Because lets face it, if the head studs are installed improperly, you've just created a problem in your attempt to prevent one.
3) Getting OEM turbochargers can be as risky if not more than even getting an eBay kit, especially if the OEM turbo has few features if any in common with the rest of the components of the "kit" you're trying to put together. Unless you A) have the mechanical inclination and resources to custom fit flanges, welded materials, etc to make these OEM turbochargers fit , and B) know exactly the type of turbocharger that you're getting that is in good condition to work with it. In many cases, getting a "cheap OEM turbo" means one main thing: its cheap, because the seller usually can't use it either.
In addition, turbo components are rarely ever worth the sum of their parts. Just because the turbo may be damaged and may need a "rebuild" doesn't mean its cost effective to do so, especially when it comes to OEM turbochargers. You can get pretty lucky with some turbo rebuild shops that specialize in OEM turbo rebuilds, but even THEY would promote the purchase of a new unit over the rebuild of the old one. It may cost a little more than what they would charge with an internal rebuild (this excludes any turbine wheels, compressor wheels, shafts, housings, etc) but you now get warranties, and piece of mind of a new unit over a used one.
Just my $0.10 .. carry on.