I think a lot of us, especially anyone playing for more than a year, has a ton of Rare Tomes they never use (or burn them on chickens during CvC) so what about something more practical? How about 10 Rare Tomes can be Exchanged for 1 Epic Tome? I'd ask about trading Epic Tomes for Leggo Tomes but Leggo Tomes are probably a high-selling item for Real World Currency.

What about Mystery Shards too? Say 100 Mystery Shards for 1 Ancient Shard? Since Mystery Shards have a 1.4% Chance to summon a Rare but 0% chance to get Epic/Legendary, I think a lot of people would do that trade. Granted, 100 Mystery Shards would get you more Summon Rush points than 1 Ancient but that's the sacrifice for convenience.

One last thing: The Bazaar needs a huge Revamp. I think I've bought 1 piece of gear from it in the past year and it was a Rank 5 Legendary Speed Piece. The other 99.999% of the time we're just checking periodically for the Ancient Shards that become available and buy the Mystery Shards if for nothing else than to do the Daily Quest. Maybe the Bazaar could be upgradeable like the Mine? Get a faster Refresh Rate and maybe a 1 in 1000 Chance of a Void Shard for 2 Million Silver or something?