My son will be getting a guitar for his birthday and he will need some lessons to learn how to play it, as neither me or his father can play. However, that is a large expense and so I am hoping that we can find some good alternatives.
The guitar actually came with a link to a website that gives lessons and so that will be a good place to start. We have also bought him a book, which he can work through and hopefully start the basics. We are also lucky in that he has a teacher at school that may help him learn as well. I have also spotted a Freehand Guitar Tablature at musician's friend where you can plug in to your computer and see sheet music that you can use to play along with the tunes given.
I do know people who pay out a lot of money for music lessons. The unfortunate thing is that many children give up at quite a young age and the money is wasted. It is therefore worth trying to find some free lessons if you can. It is also good to make a wise choice of instrument, something cool like a guitar might be better than an orchestral instrument. Something portable, may also be better.