I notice stocks are high priced here but those cubes with pigs/chicken/cow or vegetable images seem popular and cheap. Do those essentially convert water into a stock? Or are they more of a soup base or special thai flavoring?

I think they are generically called stock cubes 

Here are the ingredients for Knorr chicken stock cubes:

 

Salt, Hydrogenated Palm Fat, Corn Starch, Flavor Enhancers (Mono Sodium Glutamate E621, Disodium Inosinate E631, Disodium Guanylate E627), Sugar, Onion Powder, Nature Identical Chicken Flavors, Spices (Cinnamon), Caramel Color (E150d), Spice Oleoresins (Curcuma, black Pepper, Garlic, ginger, Clove) , Dried Chicken Meat

 

In other words, nothing like real stock, but more like something Victor von Frankenstein might knock up.