My question is; would it be financially worth it to rent out a place in Poland, or would the rent for appartments costing so little be too miniscule to bother with?
Have to agree with the others here. First of all, you're not going to be able to buy anything rentable for 30,000 AUD. You'll need at least three or four times as much to buy a decent one-bedroom apartment.
Second of all, unless you have ABUNDANT experience buying and renting out real estate in distant countries, and very good knowledge of the local market, the chances of you ever making even a single penny on this investment are zero.
Sorry to burst your bubble, but your plan is, frankly, doomed to failure. There is no point in pursuing it any further. Invest in something you know about.
Real estate is not for dilettantes. All the more so real estate way on the other side of the planet.