Depending on the type of sauna you're interested in, a few websites that sell the products directly also have reveiws for them. For example, Amazon and Wayfair both sell outdoor saunas and allow customers to review them.
There are literally hundred of websites where you can seek information on hydro hot tubs, these sites will provide customer testimonies and reviews for their products.
Yes, inflatable hot tubs are comfortable to sit in. You can read more reviews at hottubsaleonline.com/inflatable-hot-tubs/inflatable-hot-tubs-big-benefits-in-a-compact-size.html
Nextag lists walk in bathtubs ranging from $1500 to $5500. Several of the models have user reviews. http://www.nextag.com/walk-in-bathtub/shop-html
In order to find out more information about slipper tubs one could visit bathroom showrooms that stock this style of tub. Online sites such as that for Vintage Tub & Bath have slipper tubs advertised. To learn about the history of bath tubs, including slipper tubs, one could visit Wikipedia for further information.
Walk in tubs are usually installed by a credible plumber. You can probably find a reputable plumber by looking in a phone book or looking online for reviews of certain plumbers in your area.
One can find reviews on Notebook by going to said product's page and looking at the reviews section of the notebook that one wishes to find reviews on.
One can find reviews about buttock implants on the 'RealSelf' website where they have reviews from users of the site. One can also find reviews on 'American Health & Beauty'.
One could find plastic tubs in a variety of locations depending on what type of tubs one is looking for. The most likely location would be a home improvement store such as Lowe's or The Home Depot.
One can find reviews for the website Peachescam online at various other websites. One can find reviews for the website Peachescam at websites such as Alexa and XOM Website Reviews.
One can find iPod docking station reviews on the 'Digital Trends' website where they reviews for a number of docks. One can find customer reviews for them on 'Amazon'.
Weigh all of your options and prices on hot tubs by exploring online and just checking around with others who have bought them. Read reviews on previously bought hot tubs and check E-bay.