Steve,
Not an issue with prints or canvases,etc. The greeting cards are printed some where else and won't be ideal. If you have a calibrated screen than you're good to go. On the other hand, as I've posted many times, the buyers don't have calibrated screens, so it's really not important. If your monitor is close,then you're ready, no need for a test print. What comes out from N.C printers may or may not be exact, but doesn't matter, it's very close. Just upload the right files and colorspace and relax.
Rich