So I am missing one of these mounting Bolts, was wondering if anyone had one lying around or of a replacement equivalent that you've seen online or at a box store? I've found one set for sale on ebay but I'm cheap and think $30 is way too expensive for a bolt.

Hope I'm not in the wrong section for something like this, sorry if I am!

 

First place id check would be salvage yards. If that didnt work out.... how are you with a welder and a grinder?

 

I'll bet you could find a carriage bolt close enough, then grind down the hemispherical head to a flat shape. Put a nut at the base where it screws in, install to the proper height, then tighten down the lock nut to secure.