I recently did quite a bit of research into this issue before ordering a complete set of Alu and Ti bolts for my bike. Due to the high price of Ti bolts and the limited availability of some of the bolt types and sizes I needed, I decided to do a head-to-head Excel comparison of the 5-10 bolt suppliers I had found on the Internet.
Here they are:
* Racebolts LLC -- http://www.racebolts.com
* Ti Kinetics (Ti only) -- http://www.tikinetics.com
* Redmist -- http://titaniumfasteners.com/shop/
* Mettec (Ti only) -- http://www.mettec.com/
* TekBolt (Ti only) -- http://www.tekbolt.com/
* Bike Tuning Service (Germany) -- http://home.t-online.de/home/bts.renz/homepage.htm
* Titan Concept (Germany) (Ti only) -- http://www.titan-concept.com/
* BSR (UK) -- http://www.bsr-aerotek.com
* Pro-Bolt (UK) http://www.tastynuts.com/
In the end I chose to order from Redmist (http://titaniumfasteners.com/shop/
), who had the lowest prices per bolt almost across the board (up to 50% cheaper), plus he offered to special order any type of bolt I needed. And his S&H charges are fair ($4 in the US for Priority Mail), he accepts PayPal, his website is excellent and so is his service.
BTW, I recommend against buying from suppliers who sell specifically to the bicycle market (eg SRP and the bike stores) as they tend to overcharge. Instead, go to the manufacturers themselves and get much better deals! The only reason to buy from SRP etc. is if you need a non-standard bolt that is meant specifically for bike use (eg, the specially-shaped nuts used on V-brake pad holders); such bolts will not be available from the 'standard' bolt suppliers.
Attached is a copy of the above-mentioned comparison spreadsheet.
PS Keep in mind that aluminium is both lighter and cheaper than Ti. It can easily be used for non-critical bolts such as the brake levers and shifters, cable holders etc. For a short but comprehesive article on which bolts to use where, how much you can save by using aluminium and Ti bolts, and more, go to http://weightweenies.starbike.com/articles.php?ID=16