I recently lost a set of keys to my 2014 S40.  The local lock smith duplicated the ignition key with no problem but did not have a blank for the fork lock key.  I thought I found the right blank for the folk lock key (Ilco SR61N) online but when it arrived it was not even close to a match to my key. Suzuki tells me they cannot supply a replacement fork lock key and I need to replace the lock if I want to have a spare key.  The dealer I bought the S40 from says I need part 51900-29F00 at a cost of $104 plus $89 labor to install.  Two questions  (1) Should I give up searching for a key blank  (2) If so, should I just buy the replacement lock (hopefully cheaper online as previous replies suggest) or could a locksmith replace just the cylinder in the existing lock.  

I don't see it mentioned here... so:
The key blank for the fork lock is a Silca NE10, at least for a 2002.