What would be really nice is if there was a converter villager at the entrance to the villager market.

IMO, Here are the recipes it should have:

3 Iron Ingot -> 1 Gold Ingot
1 Gold Ingot -> 3 Iron Ingot
5 Gold Ingot  -> 1 Diamond
1 Diamond -> 5 Gold Ingot
3 Diamond -> 1 Emerald
1 Emerald -> 3 Diamond

Here is an example of the value of each of these items based on the price of iron ingots:

Iron Ingots: 20 noobz
Gold Ingots: 60 noobz (20 x 3)
Diamond: 300 noobz (60 x 5)
Emerald: 900 noobz (300 x 3)
Diamond Pickaxe: 4500 noobz (900 x 5)

This also means that it takes 45 Iron Ingots to get one Emerald. Even if someone found a good price on Iron Ingots, or mined a ton of them, it would still not translate real fast. It would still take 405 Iron Ingots to make just one Emerald Block.

Why do I think this is a good idea? It is either really expensive or really hard to get emeralds. I've spent a day mining for emeralds on the first day of a mining world reset and I found 9 of them. I was competing with 3 other people in the area too. 9 emeralds doesn't buy anything worthwhile in the villager market. At that rate, I would be better off not using it and going about getting the resources to make the items myself.

Support, this was a really good thought. At first glance it looked like a bad idea, but i'd be solving a few problems.

Especially the shortage of emerald.