Any question answered...

trying to find a zero degrees rise oversize stem (as in 0 degrees in relation to steerer).

What's the best offering for the money? it's a little trickier to search for it, as they're usually -/+6.

Thomson X4 is one of the few which exist. Just move a spacer or two and get a Taiwanese net-shape forged stem in ±6°

Easton EA90 is available in 0°, similar price to a Thomson but made the right way.