We live in Mississauga and treat DE as a weekend away and have done so for decades. Others prefer to save money on accommodation and meals but live with an early daily awakening for an 07:30 arrival at the track.
The choice is yours.
The college dormitory facility in Oshawa is $80/night and has two bedrooms. Split the cost with a buddy and you are all set with a great deal. You can’t beat the price.