How do I know how much an item is worth?

[Allfourkillz]

I don't understand how people can tell so easily.

[Paar]

Expierience is how they just know that item most merchants could tell you an item just off the bat.

[Fao]

Not unless you PITCH the question at the BAT!!

[JaytB]

You can learn prices yourself by following as many popular product categories as possible on CS. Eventually you'll recognize 'trends' in pricing. Key, is checking CS at least daily over a long period of time.

[JTZ]

Here are some ways,
Look at cs
Go on forums and find a price list thread
Ask a friend or someone :)