くれ is the imperative form of くれる　and the お is the honorific.

～～しておくれ = "Do ~~ for me / to me."

This is used much more often in fiction than in real life.

"Now, I'll give you this money: (Please) sell me the turtle."

「くれ」 is the imperative form of 「くれる」　and the 「お」 is the honorific.

「Verb in te-form + おくれ」 = "Do ~~ for me / to me."

Without the 「お」, it would sound much less friendly.

「おくれ」 is used much more often in fiction than in real life -- at least in real, present-day life.

"Now, I'll give you this money; (Please) sell me the turtle."