If both are reconstituted at the same moment there is probably not much difference because it is basically the same material. The advantage of handling it yourself is that you control the exact timing and dosing. When you buy from a health spa the clock on potency and sterility has already been running for an unknown period unless they mixed it the day you picked it up, and from what I have heard that is rarely the case.
I brought a friend into peptides but he wants to go through a compounding pharmacy. His doctor is against the whole idea yet said that if he is going to proceed anyway then the compounding route is better. This leaves me wondering whether a 90-day supply of compounded versions will actually hold up better than the usual reconstituted gray-market material over that span. The pharmacy told him the liquids would stay stable past 90 days. There is already discussion about whether the common 28-day cold-storage rule is too strict, with some data showing certain sequences handle longer times and warmer conditions. Even some industry voices have said lyophilized material can sit at room temperature for years with little loss. How do the real stability and safety aspects compare between a 90-day compounded batch and the standard DIY approach across the same window?