Don’t want to purchase from a big box store, but the prices seem to increase 5x when looking at non-big box store brands.
Try RTA.com.
As a cost effective means, you may want to consider Lowes.com or HomeDepot.com. Many times you can purchase online at these big box store for a better price than in-store and receive free shipping to your home.
I have used signaturehardware.com for a few of my projects and found the quality of their products to be really good. I ordered vanities with granite tops and undermount sinks. The prices are good for that kind of quality.
I really enjoy using Wayfair. I usually send my customers there first because their search and filter tools allow the client to narrow down their options based on size, style, features, etc…