Like several of us have said , the product goes off if you don't use it in a certain amount of time , so for me id end up wasting some of the 400ml tube. On Qvc's website the 150mls is £36.52 + £3.95 P &P or they have a duo for £39.00 plus £3.95 P&P but that's on waitlist and hasn't been in stock for a while , so ive ordered from allbeauty.
I think it depends on disposable income and the fact half of it might need chucking out if it goes off. QVC always push the extra volume/added value at a good price whereas I'd prefer them to offer a standard size at a vastly reduced price and free p&p and on easy pay, delivered on a velvet cushion by someone interesting like *Kevin Spacey. It's like selling an ipad with lots of add on accessories. Once the 30 days are up QVC doesn't care if your remaining 370ml starts to smell fishy.
*other actors are available, and lovely though my Hermes chap is I reckon Kevin would offer more sparkling doorstep chat.
Never had a tube of Prolagene go off!