The Guardian crosswords are free online www.guardian.co.uk/crosswords
The Times crossword club costs about £25 to join for 12 months and fot that you get the usual daily crosswords + all the prize crosswords at the weekend - most of these can be entered online too, so you save on postage.
There is a similar club for telegraph crosswords but I'm not sure of the price - when I joined the Times about 6 months ago, Times was much better value for what you got.