I got mine from Amazon.
Ya.  Amazon do a 12 pack for £63.  Works out at £5.25 a can.  
I've found 2 tins per tank works really well. Super smooth idle, quick starting and punchy boost/top end.  God knows what rare earth, wizadry chemicals they put in it, but it seems to work.
And VCDS concurs.  When I had iffy idling, lengthy cranks followed by stumbly startups, and stuttery/hunty part throttle cruising, my long term trims (block 032) were around 2%, but after a few tins of liquiMoly, the trims are now 0%.  Can't get any better than that  

It really isn't snake oil.  If your injectors are old, it's worth a go.  If you don't notice a difference, your injectors are OK and all you've lost is £5 - £7 trying it.