The gold coin is worth around ~$15.8 USD. source? me.

basically, i googled the ppm (parts per million) of some irl metals, and looked up the current market price of those metals. then i parsed out every one of them who's price was VERY heavily skewed by economic demand. like iron for example is SO expensive relative to how abundant it is its CRAZY. and eventually arrived at an average constant ratio for "rareness" to "value"

then i looked into the terraria side of things. seeing how big a world is, how much of that is caves and how much of that is actual matter vs empty space.
then i went ahead and found out how much of each ore there is per world.

putting all that together now i had the rarity of each ore and the ratio of how valuable something "should be" in theory to how rare it is. and putting those together we arrived at a reasonable value of a crimtane bar, and seeing how much it sold in game we get a conversion rate of 1G – 15.8USD

from testing this seems very accurate, like, scarily so.
according to this rate:
a bag of chips is: ~5 ish cad
a pair of wire cutters is about ~20 cad
and an umbrella costs about 5 cad

all of which seem about right.

now to address the elephant in the room, obviously there will be outliers, like the conveyor belt, 10ft of which barely costs a dollar. which obviously is ridiculous.
but you have to keep in mind, that value is derived from sacristy and necessity, or supply and demand. and since a conveyor isn't exactly hard to get, its not exactly expensive. so while it wouldn't make sense for a large treadmill to cost a dollar irl, the 1 = 15.8 rate still stands.

much the same way that a product sold in the same country its made in would cost less than half way across the world. i guess.

:3

(if anyone wants ill also link the sheets itself)
https://docs.google.com/spreadsheets/d/1tkNkkn69CyD7ZgmKUV5YKK_4oHhzGIj7XPWVVUkpfbw/edit?usp=sharing