Deltamann:
First, Welcome to Treasure Net !!
A few years ago the retail value was $7 in VG condition. You can check "Comleted Sales" on Ebay for current sales. The coin contains .903 fine silver (.1965 oz). If silver is at $39, your coin's melt value is about the same ($7.00) after a smelter takes its cut.
Don......
At the coin club auctions that I attend twice a month, 2 Reales like yours would go regularly for $25 and up. Yours has some hairline scratches and some old damage near the date, but it should still be at least $25.