The problem is, face primer and BB cream are completely different. BB cream is tinted heavily like a foundation, and primer is merely a clear cream used to help makeup stick better.
It's sound like you need primer, not BB cream as you already wear makeup. BB cream is a sort of all in one makeup/skincare but you CAN NOT wear it over night, like with any makeup.
For BB cream, it's basically foundation, but you can put concealer on top and powder.
Primer needs foundation, and everything else.
As for price, ordering BB cream directly from korea or japan is still cheaper than the high end primers here, which you can get at sephora.