Thanks all for the comments! Some great info here and I’ve spent some time doing the research based on all your advice.
I’m going to keep my eyes peeled for a used AT4047 or 4050, a KSM32, or an Austrian OC18.
If nothing turns up, I’m just going to swallow the cost and get the OC-18 new. I can’t find a single bad review on it and it seems like a lifer purchase!