Being stricken by a cold is no fun. Body aches, fever, coughs, and nasal congestion all conspire to make life a misery when nose, throat, and chest feel like they’ve been hammered and sandpapered into submission. The usual reaction is to reach for the meds. But hey, you don’t always have to trudge off to the pharmacy to seek relief. Instead, there are a wealth of natural remedies out there that can be just as effective and often more healthy for body and soul.
Since ‘wealth’ is singular, you could just about get away with ‘is’. The point to realise is that ‘wealth’ is a particular word and quite different from for example ‘lot’.
In my view, when you use is, your stress/focus is on wealth, and when you use are, your stress/focus is on natural remedies. This confirms the answer given by Alan.