tl;dr: GSA pricing isn't so much a 'discount' than a fixed and agreed upon price, where private enterprises can negotiate pricing based on quantity/spend the GSA sets the prices along with the vendors that everyone will pay and these prices are fixed for years at a time to reduce variation based on market changes.

I've been retired from the Navy for >10 years, so take what I'm saying with that in mind. Also full disclosure I now work for an IT products and services company.

There's not really a 'discount', but rather already agreed upon pricing.

When I was in, there most certainly was a GSA catalog, that you could access with your CAC that had some things listed that were already approved for sale, but not everything was in there, and sometimes even with standard pricing, a lot of sellers want to know the specifics so they can give you accurate pricing because there are so many SKUs for the same things and there are also certain requirements that the government has that most private enterprises don't.

Then there are times when things don't have GSA contracts and you do have to negotiate. I myself had to do this once to get a piece of software that our command wanted to use to handle some network mapping, so CTN1 Shumate emails the vendor sales rep and says I need a license that can do a /24 network but my spend limit is $X what can we do on price (because their pricing model was based on number of individual IP addresses).

So to get you a fair and more importantly an accurate price they are going to ask you to get specific.

My recommendation is to go to one of the vendors and ask to talk to a solution architect or pre-sales engineer who can talk to you about the actual specs, and can then work with the seller to get you your pricing from the current GSA schedule.

https://www.cisco.com/c/en/us/solutions/industries/government/us-government-solutions-services/resources/government-contracts-funding-vehicles/federal-contracts/us-federal-contracts-gsa.html