What is the difference in value of 1943 steel pennies with D or S mintmarks compared to those with no mint mark?

In circulated condition, the presence or lack of a mint mark does not significantly change its value. US cents with no mint mark were minted in Philadelphia, where most coins are minted; therefore, cents without mint marks often are more plentiful, and have 'less' value to collectors. In the case of the 1943 steel cent, there's little extra value between the 3 mints until you get to the high grade uncirculated coins, in which case the no-mintmark coins are worth significantly more -- twice as much as the "S" mintmarks and 5 times as much as the "D" mintmarks.