How do you find Beta testers for a B2C product?

tl;dr - How do you find good beta testers? I'm looking for some Beta testers for my company's Chrome extension. Called Sleek, it does seamless checkout and gives cashback at 1400+ stores. We have some users, but are looking for folks to test the checkout capabilities in particular (which requires buying an item). I could ask friends / family, but I'm looking for random people. Any suggestions? If you want to try Sleek, just message me!!!