Cheapest??
ALA and DMSA are much cheaper than liposomal anything. glutathione, Vitamin C, Magnesium. All of the liposomal versions of these things are quite expensive.
And based on my experiences, ALA is pretty safe, as long as you pay attention to your dosing. Otherwise, it doesn't seem to clear out good metals nearly as much as DMSA can. And ALA is an otherwise beneficial supplement for people who aren't heavy metal toxic.
Whereas with DMSA, there is no reason to take it, unless you are heavy metal toxic.