There is no set value for your discs, and you would be mistaken to think that you can set a singular price and automatically get them to sell. It will depend on several factors (MIJ vs. MIS vs. MIT; MXL vs. MCC), and you should do three things to insure getting a good price, (1) make sure that all the information about the discs is in the auction including where they were made and photos of the actual spindles, (2) use media mail pricing because many people hate unnecessarily high shipping charges for mailing media, and (3) sell the media as a lot instead of as individual spindles or sell them as a multiple item auction, where people can buy more than one spindle at a time.
Now, in general:
5-pack = MIJ = MXL RG03
25-pack = MIS/MIT = MCC 02RG20
The MXLs in the 5-pack tend to be more highly valued than the MCCs, mostly because MCC can be found elsewhere under the Verbatim brand, so it's not as rare, whereas the MXLs are very rare, because those are the highly valued long serial discs.
Your discs would also be more valuable if they happen to be made in Singapore, which is also rare. If they're MIT, then not so much, because again, you can find MIT Verbatim which are the same.
Like I said, there is no set value for things like this that have been discontinued. It all depends on what you have and what people are willing to pay on any given day. You have the option of setting a low auction starting price, and let the bidders determine what it's worth, or you can try and set a value of what you think it's worth, and hope that buyers agree with that.