I have just welded sills on both sides of one of ours. The sill fills with dirt & stays damp if not cleaned out. Welding has allways been an expensive exercise as it is quite time consuming, it took me two days for both sides. I always think 'better the devil you know'. I'ts still a cheap car at the end of the day, you will need to spend between 1000 to 1500 for a decent one. I see there is a dci on ebay for over 2k! don't think he is going to sell that one any day soon.
And thats the start for a DCi. I brought mine with so many problems (see blog) for £650. Its cost me 3 times as much to fix, but having said that, my V6 one I have not spent a single penny and apart from an irratating misfire, still starts!
So, if you love the espace, Brians point maybe a valid one, considering scrap for a vehicle like that is something like £100 to £200, is it worth it?