Hey guys, I agree this final call to action is an important one and needs to be highlighted more using the "important action" button styling for the template. I'll pass this along so we can improve in a future update.
This is improved in our upcoming 8.012 update. Checkout buttons for all payment methods now use the same important action button styling as the rest of the checkout process.
Niki, the request a quote link on the product page remains unchanged, there are already two calls to action on that page to either add to cart or customize, too many of these actually end up confusing the end user into not making a purchase. The add to cart and design now are more important than the request a quote so we want to maintain that differentiation. If you want to change the styling yourself you can drop in the following snippet: