If you wear glasses already you may be exempt on safety glasses. Some labs don't mind being flexible on this as they see that your eyes are already covered, however it depends on the type of glasses as well and first lab they'll either tell you this, or ask them if your glasses are suitable.
Safety glasses a cheap, and shouldn't be more than $9. Co-op bookshops usually sell them as well. So wherever you're buying your labcoat from, they'll be selling safety glasses as well.
I brought mine years ago from a TAFE student shop.