Postal Locations

I was just at the OldFort post office an asked for the cheapest way possible to mail a shirt. The lady told me about a flat rate box that was 1.40 something. She told me to fill out the envelope so I did. Then told me it would be nearly $8 to send. I said no I asked for the 1.40 something one. An she said it would still be nearly $8. I told her never mind I could take it to where it needed to go for less than that. Since she had made me fill the envelope out she still made me pay for it. That is bad business! Why did she make me fill out the envelope 1st? Why didn’t she check to see if it would be more before making me fill out the envelope. I feel it wasn’t my fault an I shouldn’t have to pay for something I did not use!