With ebay you are often buying a pig in a poke. Some vendors are good, some are bad, and price is not a good predictor. I am not very knowlegable about Epson ink---I use canons--but with an Epson the ink choice is critical given clogging problems. never consider a generic refill kit advertiswed to work with all printers-------the ink should be formulated to work with your model Epson.
But I recommend googling "nifty stuff forums" or "steves digicams" where users are likely to have experiences with the vendors you are considering.---just google the name without the quotes. Once on this type of forum you can find some inks that users report as giving good performance and eliminate some inks where a number of people report problems with color balance, incorrect feeding,
or any other noted problem. -------so you are not buying at random but with some informed choices.
Which drops your chances of being burned greatly.
I also ask-------when you say third party inks---do you mean the ink itself and you refill or in the form of third party prefilled cartridges?-----I also recommend you list what model Epson you have.
As that makes a difference because some Epson printer models use dye based inks but most use pigment based inks.
But third party options can save you a small fortune over just using Epson OEM cartridges.
I will also give you the url for two highly respected ink websites --www.inksupply.com and also
www.alotofthings.com as these websites vend MIS and formulalabs inks. And before anyone accuses me of being a tout, I will also note I have never dealt with either site. But they are highly respected inks on the nifty stuff forums.--and have distinctly different inks for Canons and Epsons. But many good ink vendors do not vend on ebay but rather from their own websites. But many good ink vendors do also vend on ebay. But those websites with good user support and a toll free number ate often very helpful.
So by all means, compile a short list of considered vendors and then narrow it down to who you finally end up dealing with-----and good luck.