Only 20 people, huh? A digital print run wouldn't cost too much, especially if you don't go with a standard card size and make it self-mailable, like maybe a postcard, and only black ink. IMO, I don't like the typical cards that get sent out, so I would get a custom project done.
I work as a graphic designer, and my own studio, we planned our Christmas "card" (not really card per se) about 3 1/2 months ago--really. Most other companies we do Christmas project for also plan them that far in advance. You should get in contact with a graphic designer the next time for sure because you can do some really creative things, but make sure you have a budget for it. For example, for my studio's "cards," we wanted to make fun of the typical family newsletter that many people get around the holidays. We set up a photo of us wearing the same red sweatshirt with a reindeer on the front in a "family gathering" setting like decorating the tree and wrapping presents, etc. We're having multiple photos made and then we're doing a mock newsletter to "update" clients and vendors in the same style as a family newsletter all photocopied and everything so to be as cheesy as possible. (Turned out fantastic, btw.)
I can help you out if you want. PM me details of what your business is, any ideas you might have, and any other pertinent info. Give me the weekend to come up with some ideas, and if you like any of them, I'll get them printed for you and have them Fedex'd to you. (Of course I'd need a real name and address and phone number to use Fedex, and we may need to communicate by regular e-mail.) I might need any company logos you have access to if you want that on the "card." After the cards are printed, you can reimburse me via Paypal, OR I can get you an estimate from my printer and you can deposit the money for the printing to me via Paypal (I'll throw in the shipping, btw).
And just so you know I'm legit, I'm the one who designed the logo banner on this forum for Presser. I've done some other work for him as well so he can vouch for me. (--If you want to do this, reply fast because I'm leaving the country on the 22nd to spend Christmas in Brazil, and even a rush print job can take up to 2-3 days. That means you have one week at most to get them done.)