Pretty cheap, if you are after this it is the cheapest I have seen it.EB Games has it for $35 at the moment with their Crazy Clearance.
Sing Party has received mixed reviews with a Metacritic score of 60. IGN has given the game a 6.3 out of 10 saying that "while one person steps up as the main performer, others can dance, sing and clap along with the prompts on the TV screen making sure everyone at the party is rocking out together."
Full track listing available here