Where are you located ?
There are alot of places where you get camping tents, of diff sizes & shapes. Makro is one place, I'm sure Metro would have the same. Coleman is common here.
If you are in Karachi, then Sunday Bazaar is a good place to check out. There's a stall by Yaseen in the flea market area. He has 2 man tents etc.
If you are in Isb/Pindi, check out Gown House on Murree road.
If in Lahore, I would suggest you check out Makro / Metro or Nila Gumbat area. You can check out Hira Arms too.