That's because the Techs were safety bars. The New was the open comb variety. If you were bidding $35 on an Open Comb Tech and it went for $120 it is because they were very rare, made in England, and some were Tech handles on New heads (which didn't make them OC Techs). I know what you are going to say, but show me proof that an OC Tech was in wide enough production to warrant a $40 price tag before responding.
Technically the open comb tech is technically the Nacet open comb razor. most normally found with the Nacet alligator on the top cap. The design of the base plate is extremely fun. its nothing more then a tech base plate with an open comb instead of the bar, in cross section is it identical.