A peruta is the amount of the weight of half a barley grain. ( I forgot where I learned that – something to do with the beginning of Kiddushin.)
According to modern understanding, a troy ounce is 480 grains. Silver is around $16.50 per ounce today, so a grain is worth 3.4 cents. We need only half that for a peruta, so 1.7 cents. AFAIK, that’s bullion price. We need to add 60% more to make it retail price, which gives us 2.75 cents. 104 perutot is therefore $2.84