From Nick's official response:
Ultimately, it's important for us that players that choose to craft their own items do not feel their experience can be easily matched by a player that decides instead to get their item from the Auction House or in trade. The progression of finding and crafting items is the core experience we built the game to provide for our players and we will not see it devalued.

Making what players craft and level for themselves more special than what they sell to other players is a good idea. Doing it by tweaking costs isn't the way to do it, though; all it really means is that it costs $20 rather than $5 to flat-out buy a "cool rare weapon." Why not make equipment that players craft and level for themselves ACTUALLY more special?

Have heat be "typed": heat dropped by a monster of family X and status effect Y contains information about X and Y. Every time a piece of equipment levels, in addition to the regular level bonuses it receives, award it a tiny bonus based on the most common family and status effect. For example, if you level a helm while fighting nothing but fire beasts, the helm should receive a small amount of fire resist. If a sword levels at the same time, it should receive a small damage bonus towards beasts.

When equipment is upgraded via crafting, it should get reset to heat level 1 as usual, but the typed bonuses above should NOT be cleared; they should stack with each incarnation of the item. As per the new patch, if the item was bound before, it should remain bound.

When equipment is unbound (which should cost very little, if anything), ALL typed bonuses should be removed.

Optional: Replace UVs with typed bonuses.

Optional: Special enemies such as bosses could give uniquely typed heat, which if present in sufficient quantities (it doesn't have to be the most common) could grant special bonuses that don't fit in this pattern (charge time reduction, attack speed increase).

This suggestion
(1) gives players more control over specializing their own equipment,
(2) provides an incentive to craft and level your own equipment instead of purchasing it premade, and
(3) provides an incentive to enter strata that players might otherwise ignore.