Linear Technologies said about $14.
LM324 + Zener + 9 resistors + 3 capacitors would take you close to $4 to
$6, considering that the LTC2400 is 24 bits ADC, your cost is totally
proporcional to dollars per bits of resolution.
Remember that LTC2400 is quite new, less than 6 months old, some
distributors don't have it available yet since it is not consumed in
billions, but because its easy operation I believe it would has a nice
place into the marketshare of ADC's.
Wagner.

Russell McMahon wrote:
>
> Yes, LTC2400 is  a very nice product indeed but not suitable for my
> application due to the need for ultimate low cost. The processor is
> set due to other considerations and I must live withing its
> constraints while costing approx nothing at all. What I have achieved
> (see separate post) will do what I want (9 or 10 bits accuracy - 8
> probably OK) using an LM324, 9 resistors (including an amplifier and
> "reference", zener and 3 capacitors. Assembly costs and board space
> costs all add up but still far below LTC2400 cost I imagine - I
> couldn't find a price at Digikey, Pioneer or Netbuy. How much are you
> buying them for?
>
> RM