Yeah, I researched places to buy fumaric acid a while ago, and unfortunately the rules are:
- only for companies (needs a register - "CNPJ"

- is subject to analysis of the register numbeer to check if related to the field/applies for the purchase.
- if approved, one must pay a "special transportation" shipping (meant for hazardous chemicals) that is very expensive.
(The funniest thing is that it's used to make candy)
So, quite similar to buying quality solvents here. 15 years ago we used to buy any solvent at the counter from chemical suppliers...
If you have any contact that can be shared, please PM me.
Additional question: do you believe there's any advantage of using other polar solvent (like ethanol) instead of water to make it easier to dry?
Thanks!