Wait for a Steam sale (Summer/Winter sale). The Sims 3 base game often drops to $4.99 .
Here’s an informative review of the so-called — including what it claims, what you actually get, and the serious risks involved. Sims 3 Highly Compressed 100mb Download
At first, it looked like the Sims 3 he remembered, but the "compression" had done more than just shrink the file size. The grass was a single, flat shade of neon green. The houses had no textures, just gray polygons. But the weirdest part was the Sims themselves. Wait for a Steam sale (Summer/Winter sale)
If you want to play The Sims 3 safely without risking your computer's security, consider these alternatives: what you actually get
Small EXE files that then download the several gigabytes of actual game data from a secondary server.