The in-ear I've tried that resembles the TH cans the closest would be the JVC woodie range, particularly the 850 variant (1100 is better, but the signature is darker), though they're universal fit only. The Campfire Audio Lyra also comes to mind. Not as technically proficient as the Jupiter and Andromeda above it, but it's got that "swing" in its sound, particular bass frequencies. Also not a custom, unfortunately.
I've got a FitEar MH335DW, which I picked over all other customs I auditioned (Noble K10 included) mainly because of the way it renders low frequencies and how much it sounds like a dynamic driver setup (attacks, decays, less "hardness" in its sound), despite being balanced armature. Having said that, it's still a different kind of presentation, and generally hard to procure outside Japan and a select few Asian countries that have official resellers.