When I looked, they're all pretty close in price. Maybe $5-10 difference between the VCH and the non VCH clinics. I think it really all comes down to convenience. Some of the grocery store ones only operate certain days of the week, while the VCH ones require appointments weeks out. I ended up going to Mid Main Medical Clinic to get mine (they have a dedicated travel clinic) just because they had an opening at short notice I gave them.

Most of the travel clinic websites have pricing if you want to compare.