Piotrkowska Street! The best, the longest shopping and fun street in Europe :) ..best pubs, discos.. best fun! U must see it!

As far as I know, the cheapest place to stay in Oświęcim is Hotel Kamieniec (see http://www.hotel-kamieniec.com.pl/). Public transport to and from the hotel might be a pain (the buses are very rare), but the Auschwitz museum is within walking distance and if you want to go anywhere else you may find that the price of accomodation + taxi might still come out cheaper and more convenient than spending the night elsewhere. As long as you're not going outside of Oswiecim it's unlikely that a taxi trip will cost you more than around 15zl, so keep that in mind when you calculate costs.
Most people, however, stay in Kraków (which has a lot more tourist sites than Oświęcim) and take the bus to the Auschwitz museum from there.

As for the Auschwitz museum itself it is one of few places in my life which I left and thought "everyone should see this" and everyone I know who has been there says the same. Even if you're not the sort of tourist that does museums and tourist sites you will not regret coming to this one.

When in Poland, make sure you can ask the waitress: "Pani, ma yakeesh canapki?" This will get you far!!!! hee heee

The Teatr Wielki in Warsaw has some of the best balley in Europe and it is considerably cheaper than its counterparts in places like London, Berlin or Lyon.

With SKM, the commuter train, it's really easy and quick and cheap to get to both Sopot and Gdynia. AND get off the train at Gdansk Wizeszcz for shopping at galeria baltycka.

don't buy the salt lamps!

The site of the REAL Great Escape. You can see the remains of the P.O.W. camps and even see a mock up of the underground transportation system, among other cool stuff at the museum of POW martyrdom.

wanna go to a cheap club/hotel?
head for Do Studzienki Street where student's houses are - on lower floors are cheap bars/clubs and over not very epensive rooms (especially during the summer)

Plenty of mountain and valley tracks for plain tourists, hikers and experienced climbers. Getting a map would be good, but try to get it in a bookstore 'cause the locals can be a bit greedy. Watch for horse cart drivers who would love to give you a lift and then ask for ridiculous money in return.

Nice medieval castle at a lakeside. Good for some sightseeing or hiking. You can rent a sailboat, kayack or waterbike and enjoy the Tatra Mountains view, or simply take a walk or cycle around. A good place to grab a bite is a restaurant right on the other side of the road (opposite to the castle) if you want to try out some local cuisine. It is however a bit expensive for the region. So if you're not a big spender - try something a bit further from the castle.