I am frequently looking on eBay at shadowless charizards and there are several of them in that price range you mentioned in what I would consider binder quality (nice fronts but whitening on the backs) not quite NM/MINT as you say here though. I think if you aren’t finding what you are looking for on eBay in this price range, you are looking too far to the mint side of the spectrum and will need to up your offer fairly considerably.
I think in general (especially here) NM would be seen how PSA sees it. PSA 7 is NM. I just sold a PSA 8 at auction which is NM/MINT by PSA standards and that went for only just over $200. There are two PSA 7 examples which if you send them an offer you may be able to get for $~150 or so, if not perhaps keeping an eye on the PSA 7 auctions. I actually sold a 6 at auction as well that really would have looked great in a binder, and that went for under $100. . I know I see a few myself raw that are probably ~PSA 7 for sub $160, but I only try to buy them if I think they are going to get 8/9 or higher for grading and re-sale.
I may have one that meets your criteria. Let me know if you’re interested.