The Eye One with automated io robot and profiling software package is probably the top of the line package but pushes 5k real quick. I also looked at the Sis unit but thats another grand+. This is what drove me back to the onboard unit plus software comes in at around $3500.
Unless you're making several profiles a week, skip the i0. It's certainly cool and convenient, but measuring by hand isn't that inconvenient or time-consuming. That will save you about $2500, and put the i1 system cost (which can profile everything) well below the Epson option (which can only profile your printer). The other thing to consider is that you usually need at least 24 hours (and sometimes longer) for Epson prints to completely dry and the colors to stabilize enough to make a really good profile. I'm skeptical that an onboard print dryer is going to completely solve this issue...
And if you have more than one printer, it's a no-brainer--the i1 system + i0 is still cheaper than the Epson option for two printers, and can profile both of them.