I've been thinking about this myself, looked at buying:

http://www.cleanyourcar.co.uk/washin.../prod_371.html

With:
http://www.cleanyourcar.co.uk/washin.../prod_326.html

The Meguiars seems expensive against the others (£30 vs £15) - But i'm drawn to the name, i really like Meguiars products, so i'm going with what i know, unless anyone has any other suggestions??