Is there a limit on the dollar amount of a personal check?

Like the old American Express commercial: "no preset spending limit".

It is really up to the bank(s) in question how big a cheque they are willing to honour.

A larger amount would likely be held longer by a receiving institution to ensure that it cleared properly, but nothing written in law (in Canada, that I am aware of).

Not really. A bank will honor a million dollar check if there are funds there to let it clear.

As long as someone is willing to take it, you can write it! I personally wrote a check for a new car. The dealership didn't bat an eye.

Many businesses will request that you get a bank-issued check for large amounts of money. The exception is often in cases where you're not going anywhere: you can write a 50,000 check for a deposit on a new house, and you'll never have a problem, but a car dealer will probably request a counter check for the same sum.

Because of the way checks are processed, you can't write a check for $100 million or more:

https://web.archive.org/web/20150629144447/http://www.bankingquestions.com/checksyoureceived/q_limitfunds.html

The field used for 'amount' has 10 digits, so anything at/above 10^10 cents (which would require 11 digits) can't be processed, at least not by normal means.