Obviously you speak about the tech stack you use here, but your UX is absolutely perfect. I just used your product and got exactly what I wanted without even thinking. My brain didn't second-guess myself once. I didn't read anything superfluous - in fact I don't think I read anything at all. The search box and images of the phones did it all for me, and the autocomplete for search was perfect. I loved that only after I searched did it give me the option to refine (like size of model)
I usually use comparethemarket or something similar when shopping around, and it's a bit of a pain - though I only realised how much of a pain since using yours.
I don't know how much conscious thought and work you put into the UX - as you mainly talk about the tech - but it's great. Well done!