I search since a few days a T5 preheat ballast for my insulator shelf with lighting (I dream to have my homemade preheat circuit  ) but does it really exist? And if yes, where can I find it one? Also, are T5 tube I see in Canadian Tire for example made for preheat circuit?

Yes they do exist for the 'old' T5's (4-13w), see here and here.

The 'new' T5 tubes also have preheat ballasts but these are the all in one electronic type, ie they do not have a glowstarter.