The corrosion could be stopped very easily . Also if sent to NCS it would then probably grade . I'm in the $300 area .
It's hard to tell from your photograph but the "S" bears a closer look. It doesn't appear to be as open as a genuine 1909S Indian. This year/mint is know to have been counterfeited.
Good eye , I didn't even look at the S . But the loop and especially the top loop of the S should be open where the ops S seems narrow . Since these are found with added MM s the op should check to make sure it's right as it may be the shading of the pic just makes the top loop appear closed .
Kanga, lol, he didn't ask what we'd pay for the slab, he asked what we'd pay for the coin. Look, I get it. He wants something like that attributed. Yeah. If he doesn't know what he's doing, he sure does. I agree with coinman1234, she's F12. Haven't looked at the market on these in that grade, so won't chance a guess on that.
Yep, that's pretty much it. In decreasing order of importance: 1. Authenticity 2. Originality 3. Grade I always put grading last since I know I can do a reasonable job with that on most coins.
If I knew for sure it was genuine, I'd pay 50 or 60 since that's all I can afford, plus the minor corrosion on reverse is a problem for me. At least I know if I tried to sell I'd get that remark from a dealer