Bunk Beds - Reinforcing or Assembling Without Original Screws/Connectors

Our family is growing. We now have 3 kids and we are trying to save room space to fit our bedroom furnitures and clothes. My eldest and second son are seven and three years old respectively. They are growing uo so fast that my wife and I decided they should have separate beds at least. We are renting a two bedroom apartment and as of now  they can not have separate rooms, so they should be contented with separate beds only.It seemed that the most viable way is to buy a bunk bed for them. My 7 year old son could have the top bed  (according to specifications/usage of bunk beds only children ages 7 and aboive should use the top) and my 3 year old can have the bottom one.

I canvassed for new ones and the cheapest that I found was 200 (without mattresses). I tried to look for used ones in the internet and found some at 100 CAD. However, I am afraid to get one as they don't provide the actual photo. Some post photo they got online. Fortunately my colleague said thay have one in their garage that they got from a yard sale. He gave it to be for free. I just have to buy some missing parts such as screws and wooden planks.

It is hard to find the exact screw for the bunk bed so I decided to do a work-around. I used brackets to connect  the upper and lower guard rails, the foot and head boards to the four posts. The outcome was perfect. It even made the bed sturdier/stronger. See photo I have uploaded.