Polsat cards need an RSA key and boxkey to work in oscam. They are available for £200ish for the full package for 12 months. NC+ Nagra3 (CAID 0B01) work just fine without extra keys. NC+ would be your best option as you can buy a prepaid basic package for not a lot. Most of the polsat cards are fully loaded so cost more.
No idea about the spiderbox, never used one.