Sharon, there are a number of message threads discussing compounding pharmacies. I searched using "compounding pharmacies" (use the quotation marks). Here, for example:
It will depend where you live which one you might use.
When to switch over from the view of finances depends on how much you are paying for Prascend and how much the compounded costs. In my case, the cost of the compounded from my local pharmacy becomes more economical once the horse is on more than one Prascend per day. This may vary, you'll just need to get some quotes and do the math.
Maxine and Indy (PPID) and Dangles (PPID)
Canberra, Australia 2010