Buy sth for 2 dollars Vs. Buy sth with 2 dollars

Hello,

Can anyone shed more light on the differences between these two expressions:

Buy sth for 2 dollars VERSUS Buy sth with 2 dollars

I have devised the following examples:

1. I bought this toy for 2 dollars. (Sounds right to me)

2. I bought this toy with 2 dollars. (Sounds wrong to me)

3. With 2 dollars, you can buy two of these toys at Walmart. (Sounds right to me)

4. For 2 dollars, you can buy two of these toys at Walmart. (Sounds right to me)