Emeralds are not as nice as they seem. If NPC trading isn't fixed then it is going to be a massive headache.
Here are some trades you can do:
Buy
1 pair of leather pants for 2 emeralds
1 diamond chestplate for 17 emeralds
1 iron sword for 10 emeralds
4 exp. bottles for 1 emerald
1 diamond axe for 10 emeralds
6 porkchops for 1 emerald
5 glass for 1 emerald
1 shears for 3 emeralds
1 diamond pick for 11 emeralds
9 cookies for 1 emerald
Sell
21 wool for 1 emerald
Book for 1 emerald
9 iron for 1 emerald
8 gold for 1 emerald
24 paper for 1 emerald
14 raw porkchops for 1 emerald
16 raw chickens for 1 emerald
2 ender eyes for 1 emerald
4 diamonds for 1 emerald
Here are some trades you can do:
Buy
1 pair of leather pants for 2 emeralds
1 diamond chestplate for 17 emeralds
1 iron sword for 10 emeralds
4 exp. bottles for 1 emerald
1 diamond axe for 10 emeralds
6 porkchops for 1 emerald
5 glass for 1 emerald
1 shears for 3 emeralds
1 diamond pick for 11 emeralds
9 cookies for 1 emerald
Sell
21 wool for 1 emerald
Book for 1 emerald
9 iron for 1 emerald
8 gold for 1 emerald
24 paper for 1 emerald
14 raw porkchops for 1 emerald
16 raw chickens for 1 emerald
2 ender eyes for 1 emerald
4 diamonds for 1 emerald