Generally people find it difficult to refill a printer cartridge. However most people will take the difficulty due to how cheap it is to refill, rather than replace, an ink cartridge.
Yes, you can refill the lexmark black toner cartridge in your printer.
To refill Ink-jet cartridge you will need to buy a refill kit.
I do not recommend you buy and try to use refilled cartridges.
There are many sites online that tout that they sell discounted ink cartridges. I've found that the cheapest method to replace my empty cartridge is to purchase a refill kit and refill my empty cartridge. I've found that these refill kits are quite effective and much cheaper that purchasing a new cartridge.
You need to buy a kit such as those that fully reset the ink cartridge such as <a href='http://www.vividinkproducts.com/Departments/Refill-Systems/HP-364-Refill-Systems.aspx'>Ink Genie</a> for example
There are different places to buy this such as Walgreens, Wal-Mart or the printer's brand online store. There are also options to refill the ink cartridge, which is more cost effective.
It is way better to buy a couple new ink cartridges than to buy a whole new printer. No matter how much the ink, the Printer is way more expensive. They do not cancel out, the printer is more expensive.
It is when you refill your ink containers inside your printer, you usually need to go to a ink reseller to get it refilled, or you can just buy some new ones
There are several ink cartridge refill kits on the market which are suitable for Hewlett Packard cartridges. Try Costco or Best Buy. Alternatively, these kits can be purchased online, both Amazon and Ebay offer low prices.
First check with the brand of printer you use. I know with Lexmark and HP you can not refill your own cartridges because the printer will tell you it is empty and not read a new cartridge number and shut down not allowing you to print. I buy already refilled Lexmark ink from the manufacture it is a few dollars less and I recycle my old cartridges with the company. If you own an older printer you can buy ink refilling kit on eBay or Amazon even inkjet.com and you can refill your old ones and use them over and over again. You will just have to check with the brand of printer. I use to refill my old ones with a Canon printer.
My suggestion would be to check out Cartridge World online as they offer a huge selection of printer cartridges. If you have an empty one, you may even be able to refill it yourself with a kit.
You can get toner cartridge refills pretty readily online, available from Amazon, some specialty sites and even ebay. Some local stores may also carry them - try calling around your area.