Not in the trillions, but more like "25-40 billion euros or $31-50 billion" https://www.dw.com/en/how-kohl-and-gorbachev-sealed-the-deal...

Helmut Kohl negotiated a very good deal. Money was not an issue for Germany but speed and total withdrawl of the Russian troops. Germany would have paid much more. A year later and it might be too late for the reunification (Gorbachev was kicked out of the Kremlin).