Jaxx, nowhere did you mention it was for three separate books, and all the other replies assume the same as I did, i.e., we were talking about one project. In that case . . . My advice would be to commission one - if it doesn't match your taste or that concept you had in your head which you didn't explain to him properly and fully, it's easier to refuse one than three ;-)). One often finds oneself talking at cross purposes with artists & especially printers. Or so you realise later. Really, it comes down to words of one syllable. Then if you like the first cover you can go ahead with the other two. Have you self published before?
http://chrisscottwilson.co.uk