One place to find cheap toner for the HP 4200 is from HP directly. Another good place is clickinks, they usually have a good coupon towards ink and toner.
There are a lot of refiled toner on ebay or amazon maybe for the HP 15x too. I am sure one can find cheap HP 15x toner there or on special toner shops offline and online.
One can purchase cheap toner at a large variety of places and stores. For example, one could purchase cheap toner at Walmart, Staples, Amazon, and Ebay.
Cheap toner for Samsung CLP 300 can often be found online at Amazon's website, which sometimes has sales on toners. Ebay also offers this type of toner for low prices.
It is quite hard to find good, cheap printer toner. I would check Office Depot as they have the largest selection and you are guaranteed to find that one that you are looking for. They generally carry the larger brands, but it is worth it.
There are a number of retailers one could purchase cheap laser toners from. They can be purchased online from 'Cartridge People', 'Toner Giant', 'Toners4less' and 'Tonerstop'.
You can find a HP laser toner Q2613X at any good electrical appliance store, or you can go to HP's website and order it there. Alternatively, you can go to eBay or Amazon, and get it cheap there.
The cheapest source of toner cartridges may be Office Supply Outfitters. As a comparison, black toner for the HP Laserjet 5000 costs only $50, while an equivalent product sells for over $200 at Staples.
Cheap ink and toners for printers can be bought online at the usual all-purpose stores such as Amazon and eBay. There are also specialized stores for these products like Ink Technologies, Ink for Cheap, Toner Value and Toner Hub to name a few.
One tenth of 4200 micrometers is 420 micrometers.
One can find the C4127X toner online in online stores such as Amazon or eBay. In addition, one can visit the official HP website, which is the manufacturer of the printer that uses this toner.
Sites such as Apple, Ink Pal, Ink Cloners, World Class Ink, and Ink Jet Willy carry cheap laserwriter toner. If you would prefer to buy locally, you could also try stores such as Staples, Target, Walmart, and OfficeMax.
One can find and purchase Dell 3100CN toner online at the official Dell website. One can also find and purchase Dell 3100CN toner online at Amazon, Supplies Guys, and Price Grabber.