I don’t think your $7500 asking price is offensive at all. If a lefty wants a nice gun, that’s a nice gun surely worth it, and surely would be $15,000 to have a similar one built today.
The general issue is it’s a quality tool, not a collectible gun. Meaning, if it were right handed it would have 20x the potential customers not just by utility, but also because righty guns satiate a collector/investor interest that lefties, crossover stocked, and central vision guns don’t.
I’m not aware of any lefty largebore for sale in the USA at present that is at this quality at this price point. It will sell, it’s just a smaller subset of gun owners that can use it. Price wasn’t the issue, but lowering price surely helps any gun sell.