Assuming it's a standard size, there should be no problem buying replacement circlips at your local boltshop. You may need to buy a pack of more than one. Take a sample, if there is more than one; otherwise take the shaft it was fitted to.
Some paranoia for you Puddleduck.
A mate was down there earlier this year and had his Remedy stolen off his vehicle. When he reported it to the local fuzz, he was told there is at least one theft gang that has sprung up to take advantage of the number of high spec bikes visiting.
Pack good locks.
I also run my bars higher on the singlespeed as compared to a gearie.
The other thing I've used for the last 10 or 15 years, is DH bars on my singlespeeds. After feeling some disturbing flex and hearing some ominious creaking from my new XC bars as I reefed on them climbing through a technical...