Replacement Seatpost Bolts - eBay, Amazon or??? that won't rust.....

Its usually the head that rusts though ? 

Wise words from p3t3 every bolt I've taken off a piece of outdoor equipment in the last ten years has had copper grease on the threads

Some more imaginatove options:

- Take it off, clean it up with emery paper and paint it black, silver... (or whatever colour you have lying around).  I mean seriously, its just a bolt and another cannondale one will just rust again....

- Buy some copper grease and pop a blob on the bolt, then use the copper grease on every other fastener on the bike if and when you have to undo them.  

- Ignore it.  

That is why it's cheaper to pop to your local fastener supplier. There is always one near by. My local one has supplied dozens of bolts and nuts for me over the years normally for my motorcycles . I rarely buy plain steel bolts unless it requires it for tensile properties. Stainless bolts are slightly more brittle than plain steel(depending on which grade stainless you buy)

Just measure it and buy some on e-bay. They'll all be metric bolts and will be fine. Even if it is dodgy (which I very much doubt it will be) it's only being used at relatively low torque.
I've bought loads of random bolts on eBay, the biggest problem I've ever had is having to buy a bag of 10 when I only need one and now I have a box of random bolts that will likely never be used

It's strange I remember as a student buying a set of ti allen bolts for both skewers and the seat post, but they don't seem to be as common now. Less theft of saddles and wheels? 

As said, the stock bolts will be chrome plated, which wears off with use and allows the bolt to rust. Get some identical A2 stainless steel bolts from either a local or online fastener supplier (it's sometimes worth ordering extra; it normally doesn't cost much more).
Chances are the bolts will be standard metric bolts. The number after the M is the outer diameter of the thread, and the length is the length of the bolt (not including the head). If the bolts happen to be a funny length, go for a slightly longer bolt and then cut it down if need be

Find a local screws and fastener supplier. Buy stainless bolts. Take one bolt with you.

I'd drop Qwerty Cycles an email, Info [at] QwertyCycles.co.uk. They're a  UK Cannondale spares and accessories specialist, used them a couple of times and they were very helpful.

try ringing the people who run cannondalespares.com as they are a uk cannondale parts stockist. Very good site

The current one will be chrome plated plain steel. If you buy a ti or stainless one off eBay, you should be fine (if you go for ti, use plenty of anti-seize). Your biggest challenge might be working out the spec of the bolt ie thread pitch and which 'M' size it is.

Update: Tons of places sell the Cannondale 'KP300' kit which contains the screw but none of them state the bolt size .