If budget is a main concern, I suggest you don't visit Colmar as the place is designed to squeeze every Ringgit from the visitors. Food is expensive, activities is expensive and it is located so isolated for a reason. You have NO choice. For a one night trip, I suggest Frasier's Hill. More relaxing and cooler there too. You can organise hiking treks and this don't need extra money. Food is much cheaper there.

The hot spring is located on the old road to Bentong. According to the info from the net it is 8 kilometers before Bentong town. If you take the exit from Genting, option 1, you have to travel further on the old road from the interchange towards Bentong or take option 2. Exit at the first Bentong interchange and upon reaching a junction turn left here. This is the old road to KL/Genting and it is about 5 kilometers from this junction. If you are visiting and driving during the day, the drive using the old road should be pleasant right from Gombak/Setapak juction, passing the old Mimaland. You can also go onto the old road from Batu Caves road from Selayang, head to Gombak.