Red Octane is having a sale on the Guitar Hero III Wireless Les Paul Bundle for only $39.99. Shipping will vary but it shouldn't be more than $10. The sale is today only and will end at 6PM PT / 9 PM ET. As Gamestooge noted, even if you just want an extra guitar, you can always just sell the game. You can find this limited-time offer here.
In other bargain hunting related news, Amazon has put up their stock of official DualShock 3 controllers on sale. Originally retailing for $54.99, these are now on sale for $40.96 with free shipping. Take advantage of the deal here.
Source -- Red Octane via Gamestooge
Source -- Amazon
[Thanks, Jonah F. and burandon!]