1970 S Small Date Lincoln Cent Penny value is an average of $10 in circulated brown (BN), $18 in red/brown (RB) and $35 and up in Red (RD) uncirculated grades. A MS67 RD 1970-S Small Date Cent is worth around $700.
Also look for the proof version since it can be worth a few hundred dollars in the top grades.
The inner loop end of the 9 is pointing across the middle of the 7 in the date and the LIBERTY is typically weak. Another diagnostic is the 7 is the top of the 7 is more level with the 0, but die fatigue can confuse this diagnostic when the walls of the die cavity is beginning to fall.