My contractor field built my island. I used 2-30" drawer base cabinets and matching panels that I bought from the cabinet place and bought a 6" pull out spice rack from HD that I placed in the middle that just needed the door for the front. I bought the 3 island legs I needed online and my contractor used paint grade 5/4x4 pine trim to make the apron (and supporting frame to support the quartz) at the knee space part of the island.
The legs and apron trim were all painted by him to match the cabinetry which was white. I saved a lot of money buying the legs and related wood apron pieces on my own. This is the site where I bought the legs. They have a really good selection in lots of different wood species.
https://www.osbornewood.com/34-and-one-half-inches.aspx.
Your island doesn't have to be custom with a little thought putting all the parts and pieces together. The place where I bought my cabinets from were charging a lot of money for the legs.