Do i have to buy each lab notebook from mcmaster or can i buy a u of t one?(cheaper)

That depends on what course it is.

Sometimes they sell used lab notebooks with the used pages ripped out - you won't end up filling a full one anyways.

Your best bet is to ask the lab TA or coordinator directly if it is okay to use a different notebook. Generally, they would not care but ask them since they are the ones who decide how things are done.

I've got 2 lab notebooks used (about 20 pages used on both) I can sell for $10 each or $15 for the two of them if you're interested.