Depends on source, country, manufacturer, quantity, etc. The cheapest is the chinese ansomone which is around $2.40 per IU if you could get it direct. American stuff like Serostim can go for as much as $500-600 for a 126IU's (7 x 18 IU vials). It just depends.
Also, 6-8 IU's is a nice dosage but with budgets it is hard to do. So something like 4 IU's M-F (20IU's per week) over a longer period of time would be better than using it up in a short period of time. Also instead of doing 1-2 injections a day. Do 2-4 injections, just divide the dosage into it. It is lower but better b/c you have a stable supply of GH in the body all day like when we are children going through growth spurts and release 5-7 times per day adding up to about 72 IU's per week.
Take some strong stuff with it and eat like a horse to take advantage of the growth efx.