What do you want a base line single axle day cab semi, or a triple axle sleeper with all the options and a extended sleeper (kinda like a small RV inside).
You can get new day cabs for 40 to 60 thousand.
You can spend up to 200 thousand or more for the big fancy rigs.
Most fall in the 100 to 150 thousand range though new.
Get one 5-7 years old and you are looking at 20 to 60 grand for a good used one depreciation is pretty steep, its just how it goes.
It all depends on what you want, there are so many interior, engine, transmission, and other options to choose from on a semi it is nuts not like shopping for a car really.
So what it comes down to is what exactly are you looking for?