Apart from using the coupon for new accounts, there can be 10% every spending on Bing. Some companies (agencies) do help opening accounts for that and I just notice that. I just have to pay $90 for $100 I spent on Bing. Let me know if you wish to hear more about that.
yes, bing is good for advertizement and you have other option like google, yahoo ... they give also discount for ad ..