What are the stand-out monitors and audio interfaces at each price range?

[avasopht]

People often ask about what speakers are good, but I think a more useful and informative question is, "What pieces of equipment stand out at around a particular price range?"

For monitors, I'm thinking: $150, $250, $650, $1250, $10,000+
For audio interfaces: $50, $100, $200, $500, $1,000+
For headphones: $25, $75, $200, $500, $1,000+

Maybe this would be best split into separate threads?