You could try the Lyceum School if you’re based in Melbourne, or if you prefer Queensland, Brisbane North Institute of TAFE has a Course in Preliminary Spoken and Written English. The cost of this course depends on how many hours you want to spend learning. The price really depends on how much you want to learn. A short course in coversational English from a community college will cost less than $100, whereas a more intense course from a provider such as Australian College of English would cost from $346 a week.
You can take a look at all your options and compare some prices for English courses here.
Hope this helps,