[raulus]

In some ways, they're just so new that it's hard to tell with any degree of confidence.

One thing you might try if you really want to dig in here. I know that PWCC tends to auction off a lot of CSG items. So you could take a look at their weekly auctions for the last few weeks. Pick out a few pieces where you can get a good sense as to their pricing, then compare to similarly graded items from PSA and SGC. It will probably be difficult to try to nail it down to a precise amount, simply because the results will probably vary widely. That and some will suggest that being on PWCC's auction site has the possibility to also skew the results.

You will probably also want to try to stick to a similar time period as what you're considering picking up. You might find that a lot of the CSG pieces are modern items, maybe with some post-war vintage at lower grades sprinkled in. So there might not be a whole lot of data to evaluate, especially if you're looking at pre-war pieces.

But with any luck, with a bit of homework, you'll at least get a sense as to whether the discount is commonly 25%, 50%, or 75%, give or take.