If it's petrol with a concentric slave you'd be daft not to replace. Diesels have a separate external slave on top of the gearbox, so easy to do any time. Expect to pay about ÂŁ190 for a clutch, ÂŁ220 if it's a Cloverleaf or DC JTDM. ÂŁ320 for a DMF if needed. But unless the latter is noticeably sloppy and noisy there's no point replacing a good DMF. Unless it's obviously knackered you can't really be sure until the box and clutch are off.
You'll just have to shop around for best prices, they tend to vary unpredictably. Alfaworkshop are a good benchmark but you may do better. Shop4parts can be cheap, but depends. At one time, pre Brexit, I'd usually find best prices at Mr Auto but no longer and being in France and Germany your bits depend on HM Customs and queues for clearance. Be even more careful with Autodoc and their subsidiaries that sound like the're in UK but ain't. I've had a few parts from them in the past that were slow but very good value, but I've seen too many complaints about non-delivery since B-day
