You should check Craigslist for a list of used hot tubs in your area. Sometimes you might be able to find a free used hot tub in the free section as long as you are able to dismantle it and haul it yourself. If not craigslist you could find a hot tub on EBay. Lastly, you could check the classified section of any major newspaper or consider posting a want ad or flyer in papers or on community boards.
The best places to find used hot tubs online are www.ebay.com and www.craigslist.com. Many retailers don't sell used hot tubs online because hot tubs are designed to be semi-permanent and also the freight cost is extremely high and negates the money you save by buying used.
Yes, the price of used hot tubs have gone down greatly. Although you could expect this with any product. Used hot tubs cost around $100-$200.
Here's a great article from the Spa Depot about buying used hot tubs: http://www.spadepot.com/spacyclopedia/used-hot-tubs.htm
There are hot tubs available for sale on eBay, but install usually does not come with it and the purchaser will have to install it themselves. Spa Depot also has used hot tubs.
There appears to be a wide range of sites that offer hot tubs for sale in the UK. Some of the stores are Aqua Warehouse, Hot Tub Barn and Hot Spring World.
some of the retailers that sell hot tubs are usedspalot.com, and choosehottubsdirect.com. You can also find hot tubs at poolandspa.com.
At Party Pools, Atlanta Spa and Leisure, Priemer Hot Tubs, Hot Tub Choice, and Rec Warehouse, you can find discounted Hot Tubs in and around Atlanta, GA.
Buy directly from the factory once you find a model you like, the factory ends up doing the support after the sale anyway.
You can find used hot tubs on Craigslist.com for cheap prices. You need to make sure nothing is wrong with the hot tub before you buy it though. It could end up costing you more to fix it than its worth.
Spa Supplies USA‎ does repairs so sometimes has used one for sale. Check them out at 4115 L Street, Houston, TX‎ - (281) 933-3466‎
Reidy Spa sales serves southern Wisconsin: http://www.spasorhottubs.com. You can also try and online store such as Spa 'n Stuff http://www.spasnstuff.com/WI-Wisconsin-hot-tubs-spas-infrared-saunas.html. They serve all of Wisconsin.
Chemicals used in hot tubs include Bromine or chlorine. Chlorine comes in granulated forms or a liquid. Another chemical used in hot tubs is sodium bromide.