Did you lose a lot of weight, and your belt doesn’t fit anymore? Or was the selection at the store just very limited with big sizes? On the last hole on your belt? Instead of buying a new one, investigate the buckle and see if there is an easy way to remove it and simply trim off some of the belt.
I had noticed my buckle had a couple screws that attached it to the belt. I simply measured how much I wanted to take off, removed the buckle from the loop, trimmed off that amount, redrilled new screw holes, and put it back together. Voila, went from being on the second to last hole back to being comfortably in the middle again.
Be careful with cutting off too much. It’s easier to cut off not enough and correct than to cut off too much.