Gearbox replace or repair

This vehicle has five speed manual transmission.

Gearbox suddenly stopped working, making horrendous noise. Jams up, stuck in gear. Also necessary to physically force stick to keep car in gear and prevent it from jumping back to neutral.

Been diagnosed with "catastrophic gearbox failure" by several mechanics, having had details described to them, including one who tried to drive the car.

Seemingly two main options:

1. Remove old gearbox and replace (£200/$270.00) with choice of second-hand gearbox (60,000 miles, £300/$400.00) Total = £500/$660.00 (one month/three month warranty)

Remove and completely recondition existing gearbox, or replace with reconditioned gearbox and re-install = £1000 ($1,320.00) (includes a one Year warranty)

So basically, the second option being double the cost of the first.

Do I take a chance with a used gearbox and get it fitted for £500/$660.00 all in, or my existing one completely overhauled or replaced with another reconditioned gearbox, guaranteed for a year, spending £1000/$1,320.00 to fix a fifteen year-old car?
Any suggestions most welcome.

Cheers,
David.