How much does a click cost?
That very much depends upon the market and the competition. How it works is that advertisers select the keywords they wish to advertise for. In most markets there will be a number of advertisers competing against each other for the same terms. Advertisers can compete against each other for position by outbidding their rivals for what they are prepared to pay for a click.
The minimum bid value for a click can vary between £0.01p and £0.05p per click depending upon the network, but its rare that bid prices will stay anywhere near that figure. In some cases, bids can be £s rather than pence.
It is up to the individual advertisers to decide what they are prepared to bid based on factors such as their own ROI, lifetime customer value and the depth of their pockets!