I really like the site. I love that it worked just the way I expected and was able to enter my model and get a quote without having to jump through hoops first.
The only suggestion I have is that the process of adding to cart and proceeding to checkout felt like I was buying something, rather than selling something. And for a minute I was unsure if I was still in fact selling. On the cart and checkout pages I think it’s important to at least have some text to re-assure me that I am indeed selling my phone.
For example on the checkout page, the heading “Your Order” could say “How do you want to get paid?”. Another example might be changing “Checkout” to “Sell it now!”.
Prompts like this will not only be re-assuring but also help to keep the person motivated to sell.