360 got cheap, it had a $199 sku as early as 2008.
PS3 eventually got that cheap as well with its Super Slim redesign but it was until 2012 or 2013 that it hit that price.
That 360 sku was terrible value and not even that cheap. By cheap I mean valued as well anyways. A $99 PS2 was a steal and same with DS, compared with launch prices for 360 and PS3. A $249 PS3 or 360 vs. $399 PS4 and soon XB1 was a no brainer and then the holidays dropped them further without really doing anything with PS3/360.
And PS3 and 360 never got down to $149, which is fine profit for Sony/MS but it helps to explain why hardware sales trended the way they did.