If I could get some help? I was wonderung if I had done this right.Write two paragraphs about how interest rates affect our purchasing decisions.

Identify the topic sentence in each by underlining it.
I have determined that the first two sentences in each paragrapg are the topic sentences.

High interest rates discourage consumers from spending money. If you are planning to borrow, high interest rates make your idea of borrowing seem like a bad idea at that specific time. When the interest rates are high consumers are more likely to put off the purchase of expensive items such as cars and homes. If something will cost far more than it is worth because you do not have the money to buy it, then you should wait until you can afford it and stay out of debt. When interest rates are high consumers are more likely to slow down and think out their purchases before they agree to any terms.

Low interest rates affect purchasing habits as well. When interest rates are low, consumers are more likely to apply for and to take out loans to finance large purchases. Low interest rates may be more tempting to many; they choose to get that new item right then. When consumers have easier access to credit, they spend more money. In most cases, low mortgage rates equate to more home purchases, and low credit card rates cause people to spend more on credit. However, low interest rates can push the prices of things such as houses higher because there is a bigger buying demand.

Your identification of the topic sentence in each paragraph is correct.

The bold part of this sentence doesn't make sense:

If something will cost far more than it is worth because you do not have the money to buy it, then you should wait until you can afford it and stay out of debt.

You also need to work on comma usage, especially #3 here:
http://grammar.ccc.commnet.edu/grammar/commas.htm

Sorry, but you haven't actually asked a question. Would you like an explanation on how to identify the topic sentence in each paragraph?