There are many Eisenhower dollars that were minted, but the most valuable is a 1972 Type 2 Eisenhower, which commonly sells for between $50 and $90. This is an especially rare minting which, in uncirculated condition, is quite valuable.
Unfortunately for most people just starting out as coin collectors, age is not the determining factor for a coin's value. Instead, it is the rarity of the piece in question. However, there were several proof runs of the 1970's "Ike" dollars, known as "Blue Ikes." These have a higher than normal silver content (approximately 40 percent), which makes them worth slightly more for their melt value.