Only pattern (test) Ike dollars were struck in 1970 so your set could not have a coin with that date.
Their values depend on what you mean by "mint". There are several specific categories.
> If the coins are proofs with "S" mint marks and in their original packages, they're worth about $4.25 each at retail.
> If they're uncirculated coins with no mint mark or a "D", they're worth about $1.35 each.
> If they're from circulation but with almost no wear, they're worth about $1.10. You will also have no 1975 Eisenhower Dollar. In that year all the dollars were minted with the bicentennial "1776-1976" date. In 1971 and 1972 the proof dollars were minted in 40% silver and in 1973 and 1974 there both 40% silver and C/N proofs. The silver proofs are often called "Brown Box Ikes" because of the mint packaging. The silver 1973-S lists for about $30. There were also uncirculated 40% silver dollars issued in special blue envelopes (Blue Ikes) that are worth a bit more than a CN clad uncirculated dollar. All of the 40% silver dollars are currently worth about $7 as precious metal. Since there is not much collector demand for these, if the price of silver goes much higher many may be melted for the silver.
None of the Eisenhower dollars struck for general circulation have more than face value. Only proof and uncirculated collectors coins sold from the Mint have premiums.
The 1990 Eisenhower Commemorative Dollar was issued in proof and in mint state condition. The value of each of them ranges between $20 - $30.
If it has been circulated, it's worth a dollar. If it is a proof or uncirculated in the original mint packaging, it will be worth only a few dollars.
If it's not proof or a very high mint state coin, it's face value
No Eisenhower dollar coins regardless of date or mintmark struck for circulation contain silver and have only face value. Just some special collector coins sold from the mint were struck in 40% silver.
Unless the Eisenhower dollar came from a special mint set, it is only worth $1. If you have an "S" mint mark though, it may have come from a mint set and worth significantly more.
The mint mark on Eisenhower dollars is on the front, below Ike's neck and above the 7 in the date.
The Eisenhower dollar was a one-dollar coin issued by the United States Mint from 1971 to 1978; it was the first coin of that denomination issued by the Mint since the Peace dollar series ended in 1935.
The S above the date is the mint mark for the San Francisco mint and identifies it as a proof coin for the Eisenhower seires of dollar coins.
The mintmark on a Eisenhower dollar (if it has one) is just above the date.
The mint mark of the Denver Mint (shown as a "D") and the San Francisco Mint (shown as "S) on the Eisenhower Dollar is located on the obverse (heads) side of the coin directly beneath the bust of Eisenhower. If there is no mint mark there, then the coin was struck at the Philadelphia Mint and in this mint did not place a mint mark on the coins struck there until 1979.
San Francisco
All Denver Mint Eisenhower dollars are circulation quality, the mintmark is on the obverse just above the date.
The 1971 Eisenhower proof dollar is valued from about $10 to $65 depending upon the quality of the coin.
It was designed by the Chief Engraver of the mint, Frank Gasparro.
The mint mark on Eisenhower dollars is on the front just below Ike's neck.
Is only worth $1 unless in mint packaging.