Rollers can be re cored for around 50-75 bucks each. Because of the amount of Ryobi 3302 out there the price for new ones is pretty affordable. Look at syntex web site. The main problematic rollers are on the crestlines. They usually only get about a year before they start giving you problems. Ink should be an oil based. Normally black is affordable around 9 to 11 dollars a pound depending on volume. To start with I would buy 5 lb cans of all the mixing inks. There is about 11 of them probably more if you add 032,072 and 021 as mixing inks. They can vary in price due to pigment cost. Have a local ink vendor give you pricing and dont forget to get 10 or more lb of Reflex Blue.
Buying an ebay press could be a problem. if there is a damaged cylinder or the press or other major parts of the press are not working those presses could be just part presses. I would want to go to where they are being sold and test them for Registration maybe a dry solids test and then running at least one 11x17 full coverage with trap to verify good registration and then try running it at full speed. Check around locally for used ones. You might pay more for upfront cost but you will pay less for rigging and you have the opportunity to see what you are buying.