I would like to know what the minimum amount is that can be sued for in small claims court in Ontario.

A collection agency is harassing me for a very small amount ($45) that for various reasons I utterly refuse to pay. Are they likely to take it as far as small claims court and if so is there a minimum amount they have to sue for?

Well of course by the time it gets into court it will be a lot more than 45. They will have interst, late fees, legal fees and court fees.
So expect this to be at least several hundrend if not 400 to 500 by the time they actually sue you.

But yes they can sue for 45 if they want plus all costs.

In the end, if you legally and actually owe it, pay it now for 40 or 45 and save yourself a lot of extra cost

I am of course aware that the cost will escalate. However the cost also escalates for the agency until such time as judgement is awarded against me. So the agency is taking a risk in taking it to court. The risk is that for whatever reason they may not be able to collect. So my question is are they likely to pursue this in court for such a small amount taking into account it may just not be worth the hassle? After all they are risking their own money.