2007 Topps Mantle HR Set 401-502

Hello - I am new to Collectors Universe and have been out of collecting cards since 2007 when the card companies made them almost worthless by overproducing ( before this I purchased unopen boxes for my children 87-92 ) I was told by a Dealer that the Dark Age ran from 86-92 . Besides wanting to buy the above Mantle Set I would like to know how long did the Dark Age really last. In 2007 I went crazy buying Jeter Gold cards for $1000 and relic cards for $300- $400 apiece it was a crazy time. Looking to get back into collecting - from looking at EBAY it seems everyone is getting cards graded and there are a lot less auctions. Looks like I have a lot to learn. Thanks , Carl Memmer