Even pre-pandemic, the single-refills were in the $2-$3 range.
One note on the 10 minute limit. Only the freestyle machines seem to be able to check for that. So, in Seussland, we'd get a Diet Coke at the machine and then pour it into another cup. Then we'd get in line to get an Orange icy. Her machine only seemed to check for a valid chip. Then I'd pour half of the icy into a cup for daughter, then I'd top my cup up with the Diet Coke. I like the blend.