Used ITBS seem to be very rare. HKS,
I would stay away from the full chinese DCOE ones. KMS takes the chinese bodies and retrofits them with better butterflies and such.
https://en.kms.vankronenburg.nl/products/throttle-bodies/bodies/throttlebody-twin
Then there are
Jenvy
EFI Hardware (probably the best designed out) Throttle blades open the opposite way, tapered bore, better throttle blade angles
Borla
OER(I would stay away from these)
ETC....
A common issue with ITB is when the engine is hot on a hot day, they tend to stick slightly open and having them return to idle doesn't work. I believe the bodies expand and cause pinching, but who knows.