What is a 1910 no mint mark penny worth?

Retail is 25 cents in Good condition and $8 in Almost Uncirculated.

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A 1910 Lincoln Wheat Cent with no mint mark would have been produced in Philadelphia. According to USA Coin Book, a coin in good condition is worth about $0.30 up to about $17 in MS60 mint condition. In MS63 choice uncirculated grade, it is worth about $24. Proof coins were minted here as well and those are worth in excess of $320.