I am a bit confused by you're question, but if you are looking to buy a refilled Inkjet Cartridge [as cheaply as possible],
Walgreen's is probably the best; they generally do a good job with their refills - they charge $10.00 the refill Black, $ $15.00 to refill Tri-color. Walgreen's can refill ~ 95?f all Inkjet Cartridges on the market. There are also other refillers who do a good job, including Cartridge World & Rapid Refill, but they can not compete with Walgreen's prices.
If you're question is "and / or" asking where to buy ink to refill you're own cartridges, there are many websites that sell ink, supplies, ect. - search for "Inkjet Cartridge Refilling".
You're HP-20 Black holds 28 ml of ink.
You're HP-49 Tri-Color holds 22.8 ml of ink.
You can refill these cartridges yourself for ~ $2.00 each.
* Conversion Note: 1 gallon {ink} = 3,784 ml. The larger amount of ink you buy, the price per ml goes down.
Ink can be bought in many different sizes; from 20 ml to 1 gallon.
<PrinterInkWarehouse> sells what they call a Starter Kit;
it comes with all 4 colors of ink [Black, Yellow, Magneta, & Cyan], 2 different sized syringes, pictures, instructions, & phone [free] Tech Support; cost is ~ $ 30.00.
I have been refilling my own HP Inkjet Cartridges for ~ 4 months now; have made some Rookie Mistakes, & once, quite a mess, however,
It is costing me ~ $1.00 each to refill my HP-21 Black [05 ml]& HP-22 Tri-Color [05 ml].
It is costing me ~ $1.75 each to refill my HP-15 Black [25 ml] & HP-78 Tri-Color [19 ml].
If you do start refilling your own cartridges, the two most important things I could say {& there are more}:
01. Use the correct type of ink for you're printer. Your HP printer will need to use "Pigmented" Black - DO NOT use "Dye-Based" Black or [so-called] "Universal Inks" -
The so-called "Universal Inks" are nothing but a disaster waiting to happen - don't do it.
02. Do not overfill you're cartridges - fill to ~ 80?f capacity - no more. This is especially true when refilling Tri-Color cartridges - Overfilling will result in "Cross-Contamination"; the colors will not print correctly.
When you reinstall the HP cartridge you have refilled yourself [or if a refiller gives you back the same cartridge you brought in], you're "Estimated Ink Levels" will show zero ink - don't worry about it - you're printer will print fine.
a HP printer "Remembers" the last two cartridges that's been in the printer {Remembers the last two Black & the last two Color}. HP has embedded a serial number in the copper conductors / strips; This is just another attempt, by HP, to discourge refilling - they do not want to share any of their 1,500? 2,000?rofit world.
If "Estimated Ink Levels" are important to you, the easiest way around this HP attempted road-block is to have 3 of each of you're cartridges - use in sequence - when the original 1st cartridge is installed, the printer will not remember it, & reconize it as "New". There are other ways around this; each HP cartridge requires a different procedure; this is all fully explained @ the weblites I will list in sources box, or you're welcome to IM or E-mail me.
Yesterday, I created a new "Yahoo / Tech Group" I named it, "Inkjet Cartridge Refillers; Individuals"; My description is, " I am creating this group in hopes of Networking with other individuals who are interested in refilling Inkjet Cartridges, from those who have never refilled, to those who want to start their own Home-Based Inkjet Refilling Business".
"This group will hopefully share information, including research, answers, & commom mistakes, to where we can all benefit" - If you want, you're welcome to join.
Good Luck,
Ken C.
"Little Covered Wagon Cartridge X-change"