...at $3,500 a week the price reduction would have to be huge before any legal drug wouldn't continue to create acquisitive crime to fund it
I infer from this statement that you believe that, in the case of legalization, the price would still be high enough to require crime. Do you have any reason to believe that heroin is inherently more expensive to manufacture than, say, aspirin?
Also, unless heroin addiction skews towards the top five-percenters, $3500 per week is a distant outlier.