Depends on how you define "economical." A Kona LHi board can be had for about $1,500, which is pretty middle-of-the-road for this sort of thing. It's got HDSDI on it, so it'll go to whatever grading monitor you choose. It's also got HDMI on it, if you choose to go with something like a Bravia instead of a proper grading monitor. There are valid arguments for both; it really depends on your situation which is the "right" option.
Blackmagic also makes I/O boards that are suitable for this purpose, but I've never used one myself, so I can't talk specifics. Others might be able to name a model number that they trust.