The most cost efficient to reach Haw Par Villa from Orchard Road is via bus by taking line 7 bus opposite Orchard station to Holland station then transfer to MRT to reach Haw Par Villa. If cost is not an issue it cost approximately $13 by taxi.
If you want something unique and bizarre, Haw Par village or originally known as Tiger Balm Garden is the place to be. It is a theme park filled with hundreds of colorful statues that illustrates chinese myths, folklore, and legends. Admission is free and set aside a few hours to explore the park. Last I remember the operational hours is 9am – 7pm. Make sure to check online if the schedule has changed or not.