There isn't at this time a god of wealth, exactly, but there's plenty who could fill the void. Consider:
- Poderon, as you already have thought of, since he is a god of commerce. But he's more about business and mutual benefit than about the greedy side of things. Not really a god for misers. But if you're cleric PC is good or goodly-leaning neutral, he'd fit the bill nicely.
Myna, goddess of good/ill fortune, and her fickle nature. Plenty of wealth-minded folks would revere her. But she's capricious, so you can't count on hoarding your wealth forever.
Zhühn always fills the void when a god of something is needed. He'd fabricate a new deity, name, symbol, and all, and inconspicuously grant the spells, and gradually steer the PCs toward his own ends. Personally, the only thing he could probably never grant is access to the Good domain.