IRL Pharmacy or not at all. If you have the funds/time to order and send samples to EC or likewise testing you may find a few here and there and be safe.
If you are opiate naive then stay as close to that as you can for the long term. Opiates can have an amazing positive effect on one's life. Oxycodone is particularly amazing for pain and fatique. Despite what your local news says, Oxycodone is a very safe opiate. It can be hugely forgiving. Start low and stay low and you will find a friend.
Unfortunately it seems that the markets are flooded with pressies of all types of nastiness. Fent analogues are quickly going to be mild in comparison to what is coming.