When you purchase your first card, a group is created for you on the universal audio site. In that group you can have up to 4 uad-2 cards and 4 uad-1 cards (for a total of 8 cards per group). At that point, any new plugins that you purchased are assigned to that group and authorized to run on all cards that are also assigned to that group. Now things have changed since I bought my first card, but when I purchased my card it came with a bunch of plugins - LA-2A, 1176ln, Dreamverb, etc. and I added a bunch over time. If I had to do it over, I would most certainly do one of their packages as it would save me a bit of money vs purchasing the individual plugsin. But it's good to know what you want prior to purchasing the plugs, so UA gives you 14 day demos to trial out each plug. They're also really good about extending the trial if you need more time.
Also before you make a purchase, check out JRRShop for prices. Eric is the owner and he frequently visits UA's forums and offers a discount to all forum members. The forums are here -->
http://www.chrismilne.com/uadforums/viewforum.php?f=2