I'm not sure I've ever heard of a company selling replacement blades for a knife (outside of specific warrantee replacement deals) Do some really do that??
Definitely have never heard of an aftermarket blade lol the blade IS the knife, the handle is the secondary part. Aftermarket scales, sure, but an aftermarket blade? Never.
Hell, people can't seem to even get replacement screws on these Drop knives, you got no chance on a replacement blade man, sorry.
How bad was the break?
Might be repairable, if it wouldn't require toooo much grinding down.
Other than that, maybe sell it cheap to someone who damaged their handle?