I have gone for it. The company I am with is New Approach and it guarantees you front page listing. However, two things:-
It is entirely key phrase sensitive,'carpet cleaners in Timbuctu' wont show at all if your key phrase is 'carpet cleaner in Timbuctu'.
It is a sponsored listing which I believe is not as good as a natural listing.
For your £99 (plus VAT) you get 5 key phrases in the first month, thereafter you can go as low as one for £20 plus VAT.
It is a rolling monthly contract. Mine started on Tuesday, so I can report in a few weeks' time whether or not it has worked for me.
I am trying it as my web designer is wanting a fortune for a revamp of the site.
On a separate note - if he has provided me with the domain name and email address, am I stuck with him?