Once you save a few more dollars with CashRewards cashback this is the cheapest RB4 BiaB has been. Nows a good time to buy so you can get some practice in before you and your mates get rat faced and play badly on Australia Day.
PS4 link: http://www.ebay.com.au/itm/Rock-Band-Rockband-4-Band-In-A-Bo…
mrbillions breaking the news with this eBay offer: https://www.ozbargain.com.au/node/227931
4% cashback from Cashrewards: https://www.ozbargain.com.au/node/227328
Buy a cheap 2nd hand guitar + rock smith and learn the guitar proper. Would cost you as much as this plus with custom DLC you have thousands of songs to learn.
Having said that. I used to hook up my electronic drum kit to RB and GH and that was some awesome fun