Citroen C4 Picasso Gearbox & Transmission Problems
Where to sell a Grand Picasso with a broken transmission?
You'll have trouble selling it without getting the transmission fixed, so I would recommend that you take it to a transmission specialist and at least get it assessed and quoted so you know what you're up for. I doubt that the trade would be interested in it, unless you could perhaps convince a Citroen dealer to trade it in. Other than that you could try selling it to a specialist Citroen wrecker. Whatever you do, you will take a bath on it if you don't fix the transmission.