If your printer is out of warranty I would consider it. I have an Epson inkjet and have started buying from local Cartridge World at about half price. No problems so far.
We have a Cannon Pixima ip6600D and they have 6 cartridges at an average cost (genuine Cannon) of £14.99 each. They last the same amount of time as the cheap ones we buy from Jet Tec but these only cost about £4 each! No loss of print quality and they last the same amount of time. Wish we'd realised the cost of replacing these cannon cartridges when we bought the bloomin thing. Lexmark just as bad ~ nearly as cheap to buy a new printer from Tesco than replace the cartridges (new printer £44.95 ~ replacement genuine Lexmark cartridges £39.00)
I get my cartridges for my Brother HL-3040-CN printer re-filled from a firm called Smart Cartridge in Hove
01273-711888
Smart Cartridge have branches all over the UK