Buy once cry once? All I know is I just ordered two more pair of DTs to use for work while traveling. I just got back from a trip to San Diego where I rucked them in and out of the ocean all week up to 7 miles a day on the same pair without washing. They are amazingly tough and treat me well. I finally did wear a hole in the heel of another pair and would bet it took over 300 miles.
You can literally buy a pair and not need to pay to replace them forever. If you want to put miles on something, they are a bargain. If you only need to use them for a few miles once a year, there may be more cost effective options.