Never had a good relationship with the buy and sell,advertised a few times buying blocks as you described above and found the response not worth the cost.I think it depends on your business , depending on your business i would put my resources into getting your website up on the search engine searches ,have you ever noticed when you search on google for example for "printing" in Dublin you get bombarded by the same few well placed results. hire someone who knows how to bump your website up to the top of the search results. someone here might point you in the right direction. WORTH A PUNT IMO.