What's the name of the song playing in Seto No Hanayome episode 24 at around 15:13?
That would be Surechigai, as composed by Takanashi Yasuharu

It was included in the Seto no Hanayome Vol.3 - Bonus BGM OST 2 album as the 8th track. 

Several of set-no-hanayome's albums are for sale on amazon So you most likely will be able to find it on there as well.