Do you intend to buy used also? Or fixated on unused?
What do you prefer more bass or neutral sounding setup? Have you auditioned any systems as of late?
PS : My own setup is a relevant 30k ish setup.
Check in dx.com there this 5.1 card for 14usd. Or you can check for a used asus or creative usb card. Or you can get a pci to usb adaptor and buy a normal sound card like asus dg.