Here is a case where using the correct botanical name might be working against you. Try searching Tabebuia alba, if seeds are available they will more likely be listed as related genus Tabebuia.
As a general observation, trees in the Bignoniaceae do not have traits lending towards becoming bonsai. There are exceptions, but if your plan is to turn this into bonsai this group may be difficult and frustrating.
If you are living where this can be grown outdoors year round, it is a tropical tree, you might have a chance at making it work, but if it has to spend winters indoors, this tree will likely fail to thrive.