Your getting some really good advise here. I wish I would have found Pond Boss before I started. Defiantly do your homework. It will pay off in the long run.
You mentioned Overton�s. Todd and all the guys at Overton�s have been helping me get my pond in shape. I would suggest checking out some of our fisheries. I�m in the Houston area but my property is in Hockley Tx. I would call Todd to make an appointment then grab the kids and drive out to Buffalo just to see his operation. I felt much better after talking with them. I went to three fisheries before I pulled the trigger. Plus I can pick up the phone and call them if I have a need. I had my first stocking delivered because of the amount I was ordering but after that I just drive up and picked them up myself to save some cash. I stocked BG, RES and FH in October. Bass, tilapia and more FH went in at the end of May in the spring. All the fish transported without any issues.
With your pond you may not have to spend near as much on fish as I did so 4k is a good starting point. The aeration will eat most of that up depending on what direction you take.