There are many available. To name just one: Creative Technology X-Fi HD Sound Card.
Do a search and check for details so it really fits you SDR.
One of the details to consider is the sample rate. I think the X-Fi HD sound card is 96 Khz sample rate.
The sample rate limits the bandwidth of your panadapter. Typically you would want as wide as possible. The highest bandwidth in a reasonably priced card is 192 Khz so you might want to check out the Creative Labs E-MU 8740A 0204 USB 2.0 Audio Interface which is 192 Khz.
And of course, some of the SDR receivers do not need a sound card and they produce wider bandwidth, some over 1 Mhz.
I am building a station now, and am not sure what hardware, but one of my criteria is at least 192 Mhz bandwidth, which is about half of any given HF band. I would like to watch CW and digital modes all at the same time, and a 96 Khz card will give about 1/4 of a given band, not quite enough.
If I get a SDR that needs a sound card I would consider the Creative Labs E-MU 8740A 0204 USB 2.0 Audio Interface. But for example the flexradios do not need a sound card. The Elecraft KX3 does need a sound card.