Polypropylene VS EPDM VS Permalon

Hi,

I'm in the process of sourcing a liner for a hole I have dug. Where I
am in Australia, a 20' x 23' sheet of EPDM will set me back about $600
US.

So, I am looking for cheaper alternatives. How does Polypropylene
compare to EPDM? And how do they compare with Permalon? Are there
other alternatives?

I haven't been able to find anyone who stocks permalon in Australia.
Do you think it would be feasible to have permalon shipped over from
the USA?

Thanks,

Han.