(I hope the link works...) it should be the search results for The Sims 3 on Origin. Pick the bundle you like the best and follow the instructions to download and you're all set!
I'm not sure if you'd be interested in this or not, but the Sims starter pack is part of the "beat the average" offers of the current Humble Bundle. www.humblebundle.com/
You can pay whatever you want, but if you pay more than the average price (currently $5) you get all 10 games shown there.