EHF RF Transmitter and Receiver
I worked for a company where we made a on-chip radar working between 57 and 64 GHz so not quite the range you need. In low volumes (less than 1000 chips per year) you should think of prices in the order of $100 per chip. As with all chips the price can go down dramatically if you buy dramatically more chips (like 100000 a year or more).

There are other companies which also sell radar chips and/or transceivers at 60 - 70 GHz. Problem is, companies like Infineon and NXP who sell these refuse to talk to small customers like you as the volumes you want aren't worth their time.

So getting chips is one problem.

Another problem is that 60-70 GHz requires RF experience and engineers which have this experience are very rare and difficult to find. All of them have jobs already.

Your best bet would be that you're in or working with some University where they have a department working with RF in or close to the frequency range you need.

Building a 60-70 GHz transmitter/receiver is work for specialists. Even building one from of-the-shelf components requires experience and knowledge. People that have these come at a price. Also they need specialist equipment. If you have to ask how much this equipment costs then you cannot afford it (price of a car, that order of magnitude, you could rent equipment though, that's not cheap either).

I'm sorry if this makes your research difficult but that's just the way it is, even though 60 GHz is getting more popular nowadays it is still a niche area in electronics which makes it expensive to use.