What opiates are you mostly buying?
Unless you are ordering Heroin, which is very expensive on SR, at that spending rate you are probably buying Oxys or Opanas.
This might surprise some, but there are much simpler and better-priced places to get those online than SR / with 24h turn-around, overnight UPS - that won't involve an eventual FBI/DEA reverse sting - which is were SR is heading with all this attention.