For major keywords like casino or blackjack the average cpc for mobile is between $0.50 and $1.50. Depending on the quality of the landingpage. For online the costs are significant higher (easily $5.00 cpc).
Also to consider is AdCenter from Microsoft. They offer similar search campaigns on both Bing and Yahoo. Best of all is that they allow you to advertise worldwide, ex. the US and Canada though.
I think the main advantage of sem campaigns is that people are looking for you, instead of you looking for them.