One problem you're going to have is that a 40 yr from 1972 hasn't been released yet. You need something released in 2012. I don't know who's putting out a new 40 yr old in 2012.
You can get a 39 yr old BenRiach distilled in 1972 though. It's about $500.
If you want something cheaper, get something distilled in 1972 but not 40 yrs old. Tobermory 32 yr old from 1972 (bottled in 2005) should be around $300.
I turn 40 in 1972 as well and was thinking about getting a 40 yr old, a 30 yr from 2002, 20 from 1992, etc. and opening them all at a big 50th birthday party, with a 50yr old perhaps.
I've started the research. I think I'll have better luck if I just get something from each decade, all distilled in 1972 of course! It will be expensive, but you only live once.