Why buy cartriges at all? Unless you got something odd or really highend?
I refill for every printer I own or owned in the last 7 yrs or so! I buy an extra set when I buy a new printer, just so if I don't feel like refilling at the time and run dry durring a printing job I can just pop in a full one.
Then the only time I buy a cartrig is if one is damaged or goes bad as is sometimes the case. Not often if you keep them full so they don't dry out, and refill before completely empty if they have the built in print heads. Extends the life of the print head if it doesn't try to print much when dry
I have on ocasion let them run dry and sit empty too, still useable most the time, just sometimes harder to get the ink to flow if it dried out and cloged a little.
HP, xerox, Cannon, very simple and easy for the ones I have had and lexmark is about the same as an HP.
What kind of printer do you have, and hows the cartrig made? Is it 3 colors in one, or seperate tanks for each color?
Cannon individual color tanks have to be about the easest I have filled. I have a I850 right now I refilled 3 times in a month or two! Hp is easy with a good kit once, then just buy inks and refill the kit
Best deal for the average user is at SAMS CLUB right now I think. 3 bottles of black, one bottle each color and two bottles photo ink (one each color) for $20. Decent sized bottles too, not like those little box kits that do 2 refills, this is alot of ink for just $20!
I use tons of ink, got a kid with her own printer too. With my refilled cartrig an I850 cannon printer and plain paper I can get what looks like photo quality to me and the wife and about everyone that looks at some of our buttons. We print our own designs for many of the pinback buttons we make, like for the local state park and some businesses. If it's a photo quality image it prints like a photo. I don't use photo inks, just CMYK.
I would never go back to buying cartriges, it is just not that hard or messy to refill most cartriges.
With the low prices of printers and the high cost of cartriges, it is well worthwhile to buy a new printer that can be easily refilled if you need to. Cost of a printer is nothing compared to cartriges. and Ink cost just a little more than water

Well almost!
As I say, I do much more printing than the average person would. I had a bit of trouble convincing the wife $160 was a great deal for a printer when I bought the I850, she was looking at the $40-$60 Hp's at Wallmart. I bought the printer and after she saw how fast it prints, the high quality of the prints, how easy it was to refill, and how long it prints before needing refilled, I got no static when I went back and bought the second one I have for a spare

I print ALOT! So does she!
I haven't had any real problems with them leaking, but you do want to plug any hole you drill with hot glue to seal them. That's the only problem I've ever really had, if you don't seal the cartrig after refilling then the ink can leak out the bottom and drip or mix with other colors. Just a little drop of hot glue seals the hole and no problem.
Pop up what printers you got and I'll look for a link for the cartriges and refill kits for it from a place I was buying from and happy with last year. Got to go look for the link for em, can't remember the name off hand. I bought some cartriges, refill kits, cordless mouse, and stuff. place several orders and was real happy with the stuff, was free shipping over $50 I think, and I got the orders in like 3-4 days by USPS. I think I have a discount coupon for them too still. Just haven't been buying for long time because I got lots of ink.