1 Injections – Testosterone injections tend to cost less than most other methods, and can range from as little as $40 a month to as high as $200 depending on dosage and frequency of injections.he only way to know for sure how much testosterone replacement therapy will cost for you is to seek consultation with a doctor or therapist. Only a professional can help you to figure the total costs of your unique needs, such as: 1  Dosage. 2  Frequency of Dosage.