Over on Facebook, Mike McGannon mentioned recently that he was utilizing "Quick Water," an acrylic water product in their terrain making as a cheaper alternative to products made specifically for the hobby model industry. I did a quick bit of research to discover some pricing and found that the below, pictured, prices are available to Prime members through Amazon. That $11.60 for a package with two 6-ounce bottles for Quick Water from Garden Splendor, $6.62 for two 4-ounce bottles in the FloraCraft Floral Accessories Acrylic Water Kit, and $7.88 for a single 12-ounce bottle of the Craft Water Floral and Craft Simulated Water Resin Kit. I also included the "reusable" Panacea Water Gel Reusable Simulated Water Setting, Medium, Crystal Clear (just because I thought it was interesting), which is a single 7-ounce bottle for $12.06 at Amazon. If you don't have a Prime account, check the other sellers including local craft stores (where coupons are available) for the best pricing.
It was the contention of the Facebook poster that a substantial saving could be made given how much of this type of product was needed. However, a quick comparison on Amazon shows that a single 16-ounce bottle of Woodland Scenics Realistic Water is available at $20.70 from Horizon Hobby with some other places comparable for those without a Prime membership. I haven't tried the above products but it looks like the one sold specifically for our hobby model crafting is is in the ballpark or better than most off-brand contenders if bought in the higher volume bottle. That seems like the way to go if you've got a handful of modular river pieces to craft.
Just to be complete, I should mention that a kit with three products is available from Vallejo. It includes a single 6.75-ounce bottle of Still Water but also a container of Water Effects and a dropper of Foam Snow for $22.37 and this is not fulfilled by Amazon, so there is no Prime deal to be had for free shipping as above. A video on the Scale War Machines YouTube channel, shows how to use this product, including tinting it for dioramas and terrain applications. Enjoy!