I vote No, the expensive ones are definitely not worth it but there are some products that will benefit your skin more than a £2 product.
A pot of cream generally has a very high water content (which is why you see aqua listed on the ingredients first) and is chock full of chemicals put there to do things like enhance the feeling of it sinking into your skin, which really isn't going to help it one bit, but will make you feel you like it more as it absorbs so easily. You also need an emulsifier to bind the water and oil content together and to thicken it to the right consistency, so that takes care of another 3-6 ingredients on the list. Then you have a humectant to help reduce water loss and a mositurising agent. Water and oil mixed together will need a preservative, so there's a couple of them as well. Finally you get an "active ingredient" that might actually do something to help your skin, but the jury is out on a lot of them.
The mark up on these products is truly frightening. Learn to make your own and you realise how horrendous it is and how really there isn't much difference between them, bar the packaging and the image built up around them. I think that Vitamin C serums can have a positive effect on your skin (but haven't tried them so can't speak from experience) and that DMAE & Alpha Lipoic Acid probaby do help them somewhat, but there won't be a jot of difference between a product containing one of them for £10 or £100 in terms of what it will actually do to your skin.
The cleansers such as Eve Lom and Liz Earle that are removed with a muslin should help your skin from the point of view that they will help remove the dirt, but they are greatly aided by the effect of gently massaging them into the skin and stimulating blood flow when you remove with the warm muslin cloth, which also will gently exfoliate.
My personal approach to this is a natural one, I make my own using good quality unrefined cold pressed oils - eg Jojoba, Rosehip, Apricot Kernal. There is one or a combination to suit all skin types - Jojoba for oily skin for example (won't clog your pores as you would think and using oil can actually reduce the amount of oil your skin produces, though you would think the opposite. Quality is defininitely the key here, look at the difference in colour between a refined Rosehip Oil and unrefined one and it is quite startling.
There are also herbal extracts and essential oils that I think do make a difference - Seabuckthorn & Echium extracts are part of my night oil. I gently massage it into slightly damp skin and it will absorb in nicely - a bit longer than a cream obviously but it will and you have a much better quality product that will over time make a difference (you need to be realistic about how much is possible) for a fraction of the cost once you have bought your initial ingredients.