Loose Screws sells replacement bolts for $4 (
http://www.loosescrews.com/index.cgi). They are keyed as you noted but saving $11 would make a few minutes with a file well worth the effort to me.
Of course you coluld just buy an M8x1.5 bolt and nut the right length at any hardware store. Wouldn't look good but would be a fast installation.
