From what i've seen most iron ingots sell for around 7r. sometimes a little more sometimes a little less. i buy them in my shop for 5r each if you want to get rid of them quickly.
He asks what they're worth, and you jump straIght to "you can sell them to me!" I thought --"how devilishly clever of him"
ah ok lol, he just mentioned he had no rupees so i thought if he's desperate i'd tell him i buy them, i did say that i thought he'd get around 7 rupees first. i don't actually resell anything - at least not directly. I use all the iron i buy for armor and tools for killing blazes and diamonds for making the tools i enchant.
I am the same way, ALMOST everything i buy or mine get's used. I do however enchant and auction now and then when money is running low. lol