Hold on a fucking minute! I hadn't seen this thing, and if I'm not mistaken, it's the gold medalist in the 2009 Most Expensive Bmx Part by Weight final. And that's with not a bit of titanium in sight, nor even an invisible titanium coating!
The 16 tooth St Martin's English sprocket weighs just 15 grams and will set you back about US$40. That's an impressive $2.67 per gram. When you consider that it's 4mm thick and 7075-t6 aluminium, 15 grams is nothing and it really makes you wonder "how did they do it, where has all the weight gone?" ....oh, I see.
Anyway... the podium is as follows:
St Martin's English Sprocket: $2.67 / g
BlueSix Titanium Brake Bolts: $1.75 / g
Kink Ceramic Headset: $1.67 / g
Well done. Very impressive. Now the first person to run them all on one bike wins.