Couple of weeks ago my son reported gearbox "gone" on his 186,000 mile Peugeot 306. Couldn't drive it, wouldn't go from first to second and so on. He abandoned ship an hour and a half from home. When I got round to getting there with a jeep to tow it home (2 weeks later) I tried it.... seemed ok to me, bit notchy maybe... drove it home. Put 2 litres gearbox oil in and it has been ok for the last week.
Now I had been searching for a gearbox etc in the meantime but the moral is check the gearbox oil level, if low top it up.... worth a try for €7.50 a litre. Quoted €180 for second hand gearbox, fitting €250+???? Good luck.