I would actually disagree with a few on there. While they are desirable, I don't think they are particularly rare or in demand. As others have indicated, modern collections are littered with carded, mint pieces and in spite of some relative difficulty in obtaining pieces, they are still common as dirt.
I find these to be mostly overpriced and overvalued:
10. Biker Scout (Clean)
13. Amidala Ascension Gun
14. Holo Darth Sidious
15. Ephant Mon
17. Space Trooper
18. Commtech Leia
19. R2-D2 w/ Holo Leia
20. Sio Bibble
Dark Trooper and Space trooper will likely prove me wrong but I think they are overpriced. The production run was likely smaller than Ephant Mon, but hard to say.
The Ep I HTF figures have never proven hard to find for me. TC-14 and holo Sidious in particular have been easy and relatively cheap. Sure, they hold more value than Anakin Pilot but really, I don't see them dramatically increasing in value. Amidala, Bibble and R2-B1 seem to hold more value, but I think even R2 is only that high because most people really like R2 units. Amidala and Bibble might well be the gems from the Episode I line. I'm surprised in that listing of Ep I stuff the pit droid 2-pack wasn't included. It's production numbers should be identical to that of TC-14, for example, so why no value??
R2 with holo Leia is grossly overpriced and over valued, IMO. Great R2 with a bonus holo mini, but really, is it hard to find on people's trade lists? Nope. Hard to find on ebay? Nope. I think this one is common as dirt. Leia commtech is a little different, but I wonder how much different? I would place its value higher, but not much. Loose versions go for around $5 on ebay. Big whoop. Yes, carded goes for more and there is more value in it that a Padme Naberrie figure, but I don't think it's going to be a trilogo General Madine 25 years from now.
What does that leave? Biker scout clean? I'm grabbing these from people carded these days for regular retail price. Hmm, not a great investment, though it does put it ahead of most other figures. I think the statements of rarity owe more to local distribution than anything else.
Ephant Mon is an interesting beast. I think tons were produced. I think MOMC versions will be tough to find simply because of the weight of the figure. But a carded version necessarily being worth a lot? No, most just ended up in hands of resellers or in hands of people that knew others that wanted them.
I think the greatest limitation to the value of these is that most collectors that want them already have them in their collections. 25 years from now we will not see a resurgence in the value of these figures as we have seen with vintage. Why? Because there will be no new trilogy to stir up memories of kids that were 5-15 when the PT came out. Other toy lines may have that kind of revival but I think even Hasbro has realized that most of the people buying this line are adult collectors. I think the focus on the OT line this year is a strong indication of that.