Below are two links describing deals for this game. I just used the first one with gamestop and ended up paying $6.54 for 2 of them to be shipped to me. My GF has been eyeing this game for a while. Hope she enjoys it.
2 Guitar Hero: On Tour Bundles for Nintendo DS for $6 + free shipping http://dealnews.com/2-Guitar-Hero-On-Tour-Bundles-for-Nintendo-DS-for-6-free-shipping/457190.html
Guitar Hero on Tour Decades for Nintendo DS for $2 + $4 s&h (updated) http://dealnews.com/Guitar-Hero-on-Tour-Decades-for-Nintendo-DS-for-2-4-s-h-updated-/454516.html --- From: CJayC | Posted: 6/3/2003 GameFAQs isn't going to be merged in with GameSpot or any other site. We're not going to strip out the soul of the site