[_ZENAS_]

I would not keep the sets together. In the years you mentioned, 90% or more of the cards aren't worth much at all. The few that are (key rookies, etc...) will be worth more in higher grades. Since these cards were so overproduced, the thing that separates a cheap version of a card and an expensive one is its grade. And the difference between a raw card in nm-mt condition and a mint or gem mint graded card is quite a bit in price. My guess is that if just sold as-is in set form, you aren't looking at more than 10-50 per set depending on the year. Whereas if you have a few key rookies in high grade, you will get much much more than that for just one card. It sounds to me like the collection itself isn't going to net you much money, but if the cards are in high grading shape, some of the stars' rookies will make you some money.