That's not bad for parts and labour Bellvecchio. The clutch parts don't cost much at all, but they take about 4-5 hours to fit so the main cost is labour.
You can change the clutch yourself but it is quite involved. You can follow a step-by-step manual such as Haynes but it is best if you can have someone helping you who has a little experience of changing clutches. Basically, you must separate the gearbox from the engine and then replace the clutch friction plate and release bearing (sometimes the clutch drive plate too if needed). You also need to buy/hire/borrow a clutch alignment tool as that makes the job so much easier.
If you can do the job yourself then it will cost you a fraction of the quote. However, it will probably take you the best part of a day. You will spend a fair bit of time under the car getting dirty and probably cursing frequently too!
If you can afford to pay someone to change the clutch I would recommend that. Certainly shop about, but I would be surprised if you found a much better quote. Clutch centres and garages change clutches all the time and they have all the tools and experience. If not, then I strongly advise that you have help from someone with some experience - and don't forget the clutch alignment tool.
Hope that helps.