Any thoughts on our sick van

It broke down a week ago with a crunching of gears and ended up getting
taken to the nearest VW garage (in Wantage) as it wouldn't start at all.
It's already had a new starter motor fitted just to get it going. They're now
saying there's a problem with the gearbox itself, which I'm not surprised
about given the noise I heard. They're now estimating it will cost about £400
if they can strip and repair the current gearbox or up to £1500 for a new gearbox.
Eeeek!

After reading the Wiki, I should have checked the gearbox oil level before.
Are we mad to keep it in the VW garage? Should we find somewhere that knows vans of this
age? Or if paying that much, maybe we could put in a new engine while we're at it!!? Sadly, I don't
have the expertise or time to do any of this myself like many of you out there.
cheers
Paul