the cheapest i find is google adwords, find some keywords, put it at 80p or whatever a click to get on page one, its pay per go so load it with 30 quid and wait, it costs me 20 or 30 a month it does retun well ish, atleast if someone searches for resrturant in your area you should be seen

you can see what clicks you have had per day and set a daily limit i set mine at 3.00