There is a place that sells fasteners called Fastenal. They have a web site and many different locations. For a bag of 100 it cost me $24. These were same as stock, but in stainless steel not the crud they come with stock. I will look up the web site and post it later.
If there is one local to you just take the bolt with you they will get the part #. If not I will post the part # when I get home tonight. Remember there are 2 different lengths of bolts. I got the short ones and they seem to work fine.