You’ve gotten some good suggestions already. I could add to it as I have over 4000 CDs (in addition to the 20 Terabytes of flac/shn files stored on external drives). You can kill two birds with one stone, depending on how your CDs are currently stored. Most people use/need/want the fancy jewel case any store bought commercial CD would come in. If you sell your CDs as you plan terrific for you, but in all likelihood you wont find a buyer for all of them, unless your price is such that you’re practically giving them away. So.... throw out the jewel case and store them in 100 pack spindles, like this https://www.amazon.com/EMPTY-CAKE-SPINDLE-100-DISCS/dp/B0089Y6WPG Then, after ripping, retain them as "backup" to whatever hard drive you rip them to. Of course, store as a flac or shn, not wav. 500 CDs takes very little space, as in less than 400 Gig. Practically any external drive would suffice. Best of luck.
EDIT:
If accurate ripping is of utmost concern, you want to use this http://www.exactaudiocopy.de/
EDIT:
If accurate ripping is of utmost concern, you want to use this http://www.exactaudiocopy.de/