Depends what you mean by options?? i.e folding wing mirrors, xenons, highline dash? or do you mean retrofit like the rear camera, RNS510...
The xenons them self are not hard to fit but if you want them legal and has they came from the factory then you'll be needing the auto leveling and headlight washers, again not hard if you have a good knowledge around cars and electrics?
The full xenon kit is expensive to put together full stop, but IMO they make the front of the car look 10 times better and I would also say put an higher resale value on the car.
The same goes for the folding wing mirrors they are expensive to buy but not that hard to fit.
The highline dash is a grey area past 2006 has the security changed so only specialist equipment can fit these, early cars are a doddle.
Xenons = £300-£400
Full xenons = between £800-£1000
Highline dash = £200-£400
Mfsw = £200-£300
RNS510 = £450-£600
Folding mirrors = £300
Heated seats = £200 (providing you have the seats with heating elements)
Rear camera = £350-£400 (you will need the RNS510 or RCD510 with video in)
Cant think of anything else.
Darren