How much is preseed?

All my friends are giving me baby fever.. Idk not like I'm in competition but I'm 24 and been with my boyfriend for 4 years. And haven't fallen pregnant.

I don't produce a lot of CM and I've read if you're not getting like wet enough it's hard for sperm to swim all the way up where they need to get. Pressed is supposed to do the CMs job and help lead them to the egg. Anyway..anyone know how much I can get it for?