Bit.Trip Saga 3DS $8.31 (Amazon) Bit.Trip Complete Wii $9.78 (Marketplace fulfillment by Amazon) FSSS
This retro-style game has received great reviews overall. At this price, I couldn't resist anymore (although I ordered for $9.99 at KMart because I had a better coupon and SYWR points).
Both Bit Trip links will (likely) default to an Amazon Marketplace seller. For the 3DS version, choose the other new offers, and you will see Amazon as the lowest price at $8.31. However, shipping is 2-4 weeks (currently available seller is $8.99).
Wii Bit. Trip Complete [amazon.com]
3DS Bit.Trip Saga [amazon.com]
As a side benefit, the Nintendo Wii's lack of HD graphics will probably be hardly noticeable on this game.