This isn't KMAG specific and it's almost embarassi

This isn't KMAG specific and it's almost embarassing but i have an issue that confuses me. How is price ultimately determined on Pinks and such. i understand the Bid and Ask concept and such but i dont know how that equates to a stock "price". It doesn't appear to be always the bid nor always the ask. Nor is there consistency with a greater number on the ask as opposed to the bid or vice versa. I have spent a while casually thinking about it but i honestly wonder by which methods it is decided the stock price. OBviously on the Greys its last trade but some of my other stocks almost seem like they're randomly made.