Cześć, Polacy. I need SIM card with internet to browse reddit and stuff. Can you advice me something?

I'm from Ukraine but currently am in Lodz on internship. I will be here for 40-60 days and need some mobile internet to communicate with friends and folks, navigate in the city and, of course, to browse reddit.

I visited some web sites. There was something like 500MB for 15pln for 30 days in Orange. But I'm not sure if I understood correctly, because my Polish is not great. Also, maybe there are some better offers out there. My co-workers didn't help so I asked you here.

Thank you in advance!

And to be sure it will work on my phone, it supports internet:
GPRS Class 12 (85.6 Kb/s)
EDGE Class 12 (236.8 Kb/s)
HSDPA 3.6 Mb/s

Edit: Bought Orange Free na karte.