Do you know if they work?
Better to test them out first before spending the money on parts and stuff.
You don't need "the d2s conversion kit with the ballast and all the goodies" as long as the ballasts and ignitors you've got there are good.
That relay harness is really all you need for the electrical part of.
I got a harness from ebay for cheap and the quality of it was actually very good, just make sure you get the one with the right connectors.
You don't HAVE to splice for the high beam solenoid, but it's nice to have that blinding flood of light when you need it.
Here's a DIY: GEN4 Projector Headlights to help get you started:
DIY Projector Headlights for GEN 4 Camry **56K WARNING**