I know my question is rather broad, but I only want to know the average wages.
Average wages are useless figures and don't really provide any real information. Overall, wages are MUCH lower in the States for the same job. VERY MUCH lower. Especially for professionals.
There are only five groups of people who earn high wages (more than 6000 PLN, net) in Poland: 1) entrepreneurs who entered the market at the right time when there was little competition and made themselves into market leaders; 2) very experienced, highly qualified professionals working in high level administrative positions; 3) very experienced, highly qualified professionals and consultants that possess skills and knowledge that are in very short supply on the Polish market; 4) very experienced, highly qualified specialist doctors and lawyers who have their own practice, for which connections, especially family connections, are extremely important; and 5) very experienced, highly qualified professionals in high level management and admistration positions for foreign companies who get paid at foreign rates.
Aside from these positions, you're looking at a ceiling of about 4000-5000 PLN a month, net, and that only after many years of experience and in mid and upper level management and administrative jobs. Entry level jobs pay half that at best, or less, if at all. Many recent grads work in unpaid internships to get experience, and consider themselves lucky that they are working at all, even if for nothing.
As for cost of living, it's not all that much cheaper than the States. Some things, like computers and electronic consumer goods, are even more expensive. Rent ranges from about 700 PLN for a no-frills room in a student apartment in a city, utilities except internet included, to double that for a studio apartment in a city, to triple or more that for a one-bedroom apartment in a city. Many recent grads live with mom and dad if they can. Rents outside of cities are lower, but job opportunities are scarcer and wages are lower, too.
Food for a young male will cost 500-600 PLN for spartan eat-at home potato-and-macaroni-based dining, to double that for a better meat-based diet. Public transport will cost anywhere between 60 to 100 PLN a month. Few recent grads can afford a car.
For a single person, 1000 PLN net would be poverty existence. 2000 PLN would be spartan and no frills in the countryside, and poverty existence in the cities. 3000 PLN would be good in the countryside, but spartan and no-frills in the cities. Very few recent grads earn more than that.
The index you should be looking at is how many DOLLARS you can put away as savings at the end of the month. Few Poles can put away 300 dollars or more, and most can only put a little on the side for a rainy day fund, if that.
If you want to compare Poland to the States, compare it with small-town Walmart-is-the-only-business-in-town Alabama and Mississippi. Opportunities are scarce, and wages are low enough that most Poles have seriously considered working abroad, and many do. It's an extremely hostile and competitive job market that has little to offer American job seekers, unless they are very experienced and highly qualified. And lucky.