Welcome,
Where are you located? That determines sources of supply..,
What is the "gadget"? (Any rf involved)?
Is the 0V of the 32Vdc supply common to the 0V of the 7.5Vdc supply or must they be isolated?
Is either end of the 4Vac supply common to the other two?
Starting from USB makes it hard, especially to get AC.
Hereabouts, there are hundreds of surplus wall-wart plug-pack power supplies available for less than the price of a cup 0f coffee in various thrift shops (typical price = 1$). I could find two DC wall-warts and an AC wall-wart and have this project done for $3 and a trip to town.
Come to think of it, I have seen some power supplies at the thrift shop that came with throwaway Inkjet printers that had multiple outputs near your requirements...