Yes, get "Dreadball Deluxe" as it contains all of the basic game and two starting teams, and then buys books/expansions/teams as required. Mantic has actually begun to run out of components for this latest print run of the base box, so they are only selling a "special edition" that includes a limited edition mini-expansion and replaces the default shiny futuristic pitch with a forest version. I'm sure you can can the normal edition cheaply enough from other retailers.
http://www.manticgames.com/mantic-shop/pre-order/dreadball/product/limited-edition-dreadball-azure-forest.html
Dreadball Ultimate contains the season 3 rulebook, enough 'big guys' to play a multiplayer game including them and the required new pitch and cards, so I'd get that rather than the individual components.
Of course, you can just get it all in one big bundle:
http://www.manticgames.com/mantic-shop/pre-order/dreadball/product/azure-primalball-viii-limited-edition-dreadball-mega-bundle.html
Which is the £60 'special edition' normal version, the £40 expansion, and the season 2 rulebook, a Giant MVP and 2 other MVPs thrown in free.