I have used them in the past with zero problems but if your just looking for straight forward washing products just hit the local Autozone
or something similar. Pick up a quality soap and get yourself a bucket which is only a few bucks usually and a nice microfiber washmit, two if you want to use a separate one for the fenderwells and wheels(what I do) and some decent waffle weave towels for drying. For strictly washing products you will save a ton with very little noticable difference between the stuff you'll order for Autogeek
or your local parts store. When it comes to waxing etc that is whole other subject and I recommend higher end products but simple washing products can be had much cheaper locally. I usually use Autozone because every couple of weeks they run a special on Eagle One products where it's 2 for $6 no matter what you get. So that's usually when I load up on soap, AtoZ wheel cleaner(Stuff works great, never damages wheels and cuts wheel cleaning time in half) and the Wax As You Dry(Another awesome product) and window cleaner etc. I usually can get a couple months worth of supplies for both my vehicles and motorcycle for $30 or so. The two bucket method sounds great but as time passes you will grow tired of it and go back to a single bucket. As long as you use enough water and soap in the bucket you will be fine with one. Just my .02.