Cheapoair.com Wanted to charge me $175 to change the date of my flight and the ticket cost me $145, Internet

All airlines offer their lowest fares on non-refundable tickets, which is what you buy at most bargain online travel sites.    A non-refundable ticket is good only for the flight is was booked, which is why you should be absolutely certian that you're going to be on that flight before buying.    Other types of tickets can be changed or credited, but you will pay more for those.   Sometimes up to twice as much.

  Bottom line :  If you're going to pretend to be your own travel agent, you should know a bit more about how these things work. 

CANCEL AND EXCHANGE All airline tickets are 100% non-refundable. In certain cases where the airline may allow cancellations, a credit may be valid towards a future ticket purchase by the same traveler with travel on the same airline. An applicable penalty and a fare difference (if any), will be added in these cases. Usually the credit issued by the airline supplier is valid with time constraints and a specific expiration date and should be discussed with a customer service agent. All such bookings where the cancellation may be permitted must be cancelled prior to the scheduled departure time of the first flight segment by calling our customer service center. We do not guarantee any cancellation. A cancellation fee of $50 per person per ticket must be paid to us at the time of cancelling the booking; we retain this fee. The credit will be held for a limited time period, please ask the customer service agent for the specific date by when you must use this credit or you will lose the credit amount. When you are ready to make the new booking, you will have to the pay fare difference (if any), applicable airline penalties for that fare and CheapOair's exchange fees. All such changes are governed by the airlines' rules and regulations and are out of our control. CheapOair does not provide any representations or guarantees on changes or fees. If you are cancelling the booking and applying for a refund please read our Refunds Policy. Read more about our Change Policy if you wish to exchange the tickets for new dates or routing.

No additional representation is made for our exchange fees except that an agent will assist you in locating your desired new flights and attempt to re-book the new flights based on availability and other factors.