The Danlac website is pretty easy to navigate and has a section to choose which cheese you'd like to make, then lists the starters available for it. You can buy from the site, but you might also like to price shop, though all the cultures from different suppliers seem pretty consistent. There is one little math trick to the DVI cultures from Danisco, which is, the package will say something like 125 DCU (Danisco Culture Unit). This package will acidify 1250 liters of milk (basically 1 DCU will acidify 10 liters of milk). Take the package weight, which is printed on the bag, divide it by 1250, and now you know how many grams of culture per liter that you need. Hang on, there's one last step. Finally, multiply that gram per liter by the amount of milk you are using, and now you know exactly how much culture to weigh out. It may seem a little tricky, but it is easy once you do it a few times (I do it three times a week for 500+ liters). You could easily create a spreadsheet and plug in the numbers to have it calculate for you.
Finally, Sailor posted a great thread on making mother cultures from DVI cultures. I personally don't do this for various reasons, but it'll be a money saver on cultures!
Sorry for not posting any links, I'm doing this on my phone with limited time. If you have any more questions ask away.