just about any mixing system should do OK. They all have their small issues that you have to learn to live with and find workarounds for.
We use the Union Unimatch which is a simulated process ink. It prints very well wet on wet and it blends great, but it is a lower opacity ink and will require an underbase for most prints. Cool part is you used to be able to get a sample kit with everything needed for very little money. It came in quarts or gallons. Going for the quart version, you could try it out for just few hundred bucks. I don't know if they still offer it, but it's worth a phone call. . .
pierre