That's a good price. I was looking on ebay and could only find pigment ink at about £25 for 4x100ml. I'll bookmark the page and hope the special offer is still on when I have £20 spare.
I don't know why you would have been sold dye ink to replace Durabrite. I know the first version of Durabrite was a bit of an abomination - it didn't do well with photographs and it clogged a lot, which led to Epson reformulating it. I think that's when they renamed it to "Durabrite Ultra".
With Durabrite in entry-level printers and Ultrachrome in higher-end printers, Epson were pushing heavily into the pigment market - extolling its fade resistant durabilities over dye-based ink - but then they suddenly came out with Claria, which they then pushed on the grounds that it was better than Durabrite, yet they still sell Durabrite.
Hard to know what's going on in their heads sometimes.
The primary difference between a pigment ink like Ultrachrome/Durabrite and a dye ink like Claria is in the fade resistance. Pigment is inherently fade resistant and so can survive quite well no matter what you print it on. A dye ink can be fade resistant if used with the correct paper - which is why you see names such as Claria (Epson), Innobella (Brother), and Vivera (HP) used on both ink and paper. If you use both together, you'll get good fade resistance. If you use one on its own, then you won't.
But then if the item in question is mostly worn indoors, then even a dye print will last reasonably well. It's usually a weakness to ultraviolet that increases fading.
A good place to read up on the fade resistance of OEM inksets/paper is
http://www.wilhelm-research.com/
