Just my opinion... I would not rely on each of these categories alone - but together it should tell you which one to buy:
1. Have them run the report from the printer that shows how many firings per channel.
2. Ask them about what maintenance they've run since they owned it (for example, replaced the heads, dampers or any of the boards)
3. The 7800 is a newer model - but it has a pressurized ink system. If you go with this one - make sure you buy high quality bulk carts. Cheap ones will leak and cause a huge mess.
4. Make sure you buy the 9000 series printer is you plan on printing jerseys or other larger sized substrates. You'll appreciate the wider print area down the road.
True - one 9800 might not be fast enough for a full jersey mfg operation. Most major jersey companies would have an army of printers 4-9 total. What are you looking to do with this printer? Larger runs of small prints or oversize prints?
I have a one source for cut/sew jerseys (looking for others), so I would mainly be doing other sublimated things, like white based shirts, towels, etc.
I got a used 9600 a few months ago. I love it. If your not afraid of doing your own maintenance, checking the net for fixes, then get it.
However, it is SLOW!!!!!!! but the print quality is amazing.
The Epson 96XX - 98XX prnters are very reliable. Surely not as fast as some of the Mutoh and the likes. but you have to figure how many jerseys you are going to print in a day. With the right ICC profile you can get 5 long sleeve jerseys an hour out of them. Do the math - you can easily produce 1000+ jerseys a month from a single printer. That is a decent amount for a fairly small price. We do full dye sub jerseys and operate very profitably with Epson's. Be advised that serivce on these are not cheap - you can figure on $500-$1,000 per service call. You can easily do a useage print from the printer that will tell you number of pages and life expectancy left on the key parts.
There are a lot of variables involved in ink cost. It would totally depend on your ICC profile and cost per liter of ink. Sawgrass suggest a figure of approx .08 cents a square inch based on their profiles and Sublime ink.
well didnt' think of this at first, but I don't have a press big enought o handle any jerseys, and won't be able to buy one for awhile. So that point doesn't matter.
got all excited, then realized how am I going to press them, lol.
We used the power flush from Sawgrass - I think it was aout $75 for the liter but I may be off. Couple power flushes and then a few test prints to get the cleaning fluid out and you should be good to go.
7800 or a 9600?? 
