Depends.. Are mechanically inclined? If so get a long rod of grade 8 in the thread pitch you need, cut it down as you go and need. Less apt to do that and just get bolts from home Depot or whatever fastener supplier you have around you.
If this is too much then you might want to consider a different hobby, this is seriously one of the most irritating things to work with even without nuts and bolts problems. Toss in bent this and stripped that and you've got the equivalent of 2 women on different cycles jammed up between your legs. Half the time it won't run because of this, and half the time because of that, and the other half because the 2 of them don't get along.
Yeah, that's basically it, if you can live with one of these then marriage should actually be kinda easy when you get to it. (worthy noting I've curbstomped, ripped parts out of and tossed into the back of my truck, bashed with a hammer, drilled holes in, contemplated lighting on fire, thrown tools at, and all around downright beaten my bike near half to death. I've never done any of these to my wife. Word of warning.)