'95 Sunfire that won't park

It's a manual transmission, w/ a broken parking break. I've been parking
it in 1st gear, but today, it won't stay parked in ANY gear, even reverse.
Car runs just fine, shifts just fine. Car is completely off when I'm
attempting to park it. Any suggestions as to what's wrong? Or should I
just pony up the dough to replace the parking break??? lol :-)