Here in Australia you can get stuff from most hardwares (Bunnings usually stock it) and some craft shops called Clear Gloss, sometime Glass Coat, which is the same thing as EnviroTex Lite, I have been using it to do water effects for a couple of years now and it is great, and what's more it comes in different sizes, I've 250mL & 1L kits so you can easily and affordably even do rivers and ponds and the like on tables.
I have tried the Woodland Scenics Realistic Water which was too expensive and gave a mediocre result, and took ages to do (several layers with a days drying time each) and it shrinks when it sets, making the water not set level, and the Citadel Water Effects was utter crud that I wouldn't recommend to my worst enemy.