What do I call a person who always seeks for the best price on particular item/product/service ?
Person who spends hours digging internet to find deals/discount codes/coupons in order to pay a minimum price ?
Same person may also bargain for hours with any service provider, like a car dealer, barber or street hot-dog seller, etc.
It can be in a form of addiction but also can be considered as good quality of person (he is smart enough never to overpay)