In reply to Oujmik: Thanks for the advice all. I'm still finding it pretty bewildering, but that's mostly just because of the complexity of the package deal websites (i.e. Crystal).
For example in Alpe d'Huez and Soldeu, the price of ski hire, tuition, lift passes is all pretty similar individually, but when you buy them as a 'ski improver package' the price for AdH is almost twice as much as Soldeu! (£450pp vs £250). I guess it just comes down to what Crystal can negotiate locally.
Add into that the fact that some packages have a free lift pass, some include a lift pass and ski hire (but no boots!) with your accomodation and the fact that much of the self catering accomodation is based on about 7 people in bunk beds and sofas and you hava recipe for confusion!
I'll look into the independent option, that's how I normally do holidays, but skiing is out of my comfort zone so I'd been favouring packages.