It's good practice to distrust anyone who's trying to sell you something. No exceptions 
This is why sites such as camelcamelcamel exist. The price now is important, but not the whole story. You really need to know the price history of an item to be sure you're actually getting a "bargain".

This is why sites such as camelcamelcamel exist. The price now is important, but not the whole story. You really need to know the price history of an item to be sure you're actually getting a "bargain".