I am an old school player flipping these cards competitively since 1994. I once traded my Revised Mahamotti Djinn away for an Unlimited Mox Jet and was unhappy with the trade!

I spent 15 years building an all-premium cube with complete beta P9, 10 beta duals, and all judge promos, foils, and rarities. To the best of my knowledge this was the most premium cube ever made at the time, and was worth 41,000 at time of sale in 2011 but a down-payment on a house was a worthy cause!

***  TRADING  FOR BASIC LANDS  ***
Foil ARENA Forests (Urza's Saga symbol) need 4 more!
LORWYN Islands (#287) Foil
LORWYN Swamps (#291) Foil or non-foil
BETA or ALPHA  Lands
APAC and EURO Lands
Ice Age Snow-Covered Lands
COLLECTORS EDITION LANDS

TRADING GOOD VALUE FOR  COLLECTORS EDITION AND INTERNATIONAL EDITION CARDS

***  TRADING AWAY THESE MAGIC ONLINE CARDS  ***
(for cards on my wishlist)
RAVNICA, CITY OF GUILDS edition.
3 DARK CONFIDANTS 
4 OVERGROWN TOMBS,
4 SACRED FOUNDRIES,
4 GODLESS SHRINES.