Thick veneer is definitely not a massed produced item. Here is what I would do. Look online for a specialty lumber dealer that appears to have the raw material (in general) in stock and then give them a call to make sure they can fill your exact needs. If you can’t resaw them yourself (a useful skill to learn) l would ask the supplier if they offer milling services or find a local shop to do it for you. If you happen to be in East Tennessee drop me email and I can saw it for you if need be. If all else fails you may have to abandon using a solid single veneer and do some other configuration of pieced veneer, use another species dyed to match the look you are after, or learn decorative painting to simulate the desired look, which is a very traditional practice.
Have fun and please do post photos of your finished project.