Here is the sentence again:
Given 1,000 dollars as a graduation gift, Kris wavered between putting the
money toward a new computer or going to Germany to visit his
sister, finally Fräuleins and beer won out
over modems and megabytes.
The comma between sister and finally illegally joins two main clauses. The first main clause begins with Kris wavered ... . The second main clause is finally Fräuleins and beer won out over modems and megabytes. To join two main clauses with a comma is to create a comma splice, a major error in sentence structure.
To fix the problem, you could use a semicolon between sister and finally. Then add a comma after finally.