To dream that you or someone is buying something, represents your acceptance of an idea, condition, or situation. Consider what item you are buying for additional analysis.
Exchanging one thing of value for another thing of value. This could point to an actual recent purchase or something you'd like to purchase, or it could represent the exchange of support or encouragement within a friendship, or it could represent a situation where work or effort is exchanged for something of value (money, thanks, praise, etc.).