From a sample size of 11 products, the average hylian rupee per dollar is ≈2, and the median is 0.5 rupees per dollar. Definitely going to add to this.

Formatted: rupee cost /dollar cost rupees per dollar

Watermelon - 4/4.67 .85

Apple - 3/1.31 2.29

Carrot - 4/0.50 8

Durian - 15/30 .5

Pepper - 3/0.30 10

Pumpkin - 5/5.40 .92

Acorn - 3/free probably N/A

Goat butter - 3/7.50 .4

Milk - 3/7.00 .42

Wood - 2/8.00 .25

Flint - 5/30.00 .16