More about your being able to find a bolt for a reasonable price. Lots of milsurps have been assembled out of parts bins with zero QC, but installing another bolt isn't terribly difficult. Depending on what rifle it is, of course. It can get expensive though. A bolt head for a No. 1 Lee-Enfield runs about $30 and it takes a handful to check with headspace gauges(that run about $30 each too). More expensive with bolt that don't have separate bolt heads.
"...Most of all matching number firearms are collector grade..." No, they aren't. Not all 'matching' rifles are in decent enough condition and condition comes first when determining collectability.