I have a prediction that I didn't want to post here because, well, what do I know?
With the recent firming up of the Reserved List, also notice that every original Dual Land is on that list.
Yes. The number of "cheap" (Revised set) Dual Lands is now extremely limited instead of open for expansion.
Duals were running $20-$40 last year.
Now? Try $30 minimum, with Underground Sea being the most expensive at nearly $90!
Guys, if you have the money to get Dual Lands for around $30 each, you won't be sorry. You may not be sorry at $50 each, and if they go above $100 I'm gonna regret not telling you to get Underground Seas for that much.
So basically...if you have the money, invest NOW in original Dual Lands. They're too good to NOT be worth triple digits for the better ones (read: Blue producers) now that the Reserved List is set in stone.