I do not know the price but I can share a couple of points for you.
Many university IT departments can provide such licenses upon request. Single person licenses may be really costy. Also you may need an SPSS license beforehand as well, in order to fully use AMOS.
R is an alternative, but JASP is a freemium program which has an intuitive interface and can do the same analyses. It has many up to date resources too. JASP makes R features available without writing syntaxes. It has many extras such as survival analysis, social network analysis etc. as well. I strongly recommend you to check it out.
AMOS is commercially sold, copyright software, available as an SPSS add-on from IBM (only for Windows OS, to my knowledge). As such, there isn't a free version available. However, as Çınar Kaya correctly notes, it is possible that your institution has a site license for SPSS which would include the AMOS add-on, which might be open for student/employee use at no additional cost.
If not, do have a look at the lavaan package in R (absolutely free). I believe that both Jamovi and JASP have links to lavaan, though these may not be as fully developed as other portions of the two packages.
There are many other SEM programs available, some with "free trial" periods, and some that are free (like OpenMx). Here's a list of some of more commonly named packages that you may wish to investigate, other than AMOS: