Pharmaceutical grade products are products that are approved for sale by the fda. There is human grade and vet grade. This means that the manufacture of these products comply with GMP standards pertaining to their use. Vet grade products will be labeled "not for human consumption" but will meet veterinary standards.
The price is dependent on different brands, branded/generic, 1st vs 2nd vs 3rd world countries, government subsidies/insurance etc.
Btw, the testosterone will take about 4 weeks to reach peak levels(see half life) so it's still too early to fully feel the effects.