I have no idea when it actually happened, but I just found the entire Black Sabbath catalogue on Rhapsody. For years the earliest you could listen to was Born Again and later. I think Born Again was the last great Sabbath album, but that may be because I love Gillan and, well, it’s a fucking awesome album. I was pretty let down by Seventh Star and it was the last Sabbath I bought.
But now, (or sometime within the past year or so) it’s all there. 
The Devilling knows a lot more Grateful Dead and Pink Floyd than the average four year old; I think it’s time to teach him to throw his little fist in the air.