Strangely, with all the sites out there dedicated to e-book covers, I found very few pre-made covers that immediately drew my eye right to them. And the ones that did, had models with blonde hair--both Alex and Hayden have dark hair!
I love the covers Sarah designs at Okay Creations, but she does not show pre-made covers on her site. For my first book, I felt unsure of what I really wanted (though I knew I'd know when I saw it). I'm the same way with everything. Anyway...had I contacted Okay Creations, I did not want to be vague in what I wanted or be let down if what she created did not reflect what I envisioned.
So...I searched elsewhere for pre-made covers. I really liked one at Mayhem Cover Creations and also found one through The Book Cover Designer I contemplated. I wasn't sure if the cover models resembled the characters I had in my head, but really liked both.
(This information can also be found under About Self Publishing)