Get online and search out Machine tool suppliers, and Machine Shop Supplies, in the Ottawa area.
Bound to be a fair few around the city even still.
You get to choose right off the bat, if you want an integrally mounted chuck (the threading is built directly in the back of the chuck), or you want to put together a chuck and a back plate that need to be fitted together. The former are a bit shorter a package, while the latter allow you a LOT of flexibility in choosing what suits your needs, rather than just what comes already threaded for your spindle.
1 1/2 inch, 8 threads per inch, is a REALLY common size, if you are looking to be cheap and willing to take at least a minor risk, check out ebay as well as about any machining related site that has a buy and sell option on it, to see what is out there. Gives you a chance to see what the going rates are so you have a better idea what to expect to pay.
If you just want something cheap and OK, check out Busy Bee and see what they can supply. Likely Chinese, possibly India Made. Inexpensive and serviceable, if not very polished. At worst, you will have to clean the new chuck out, give it a decent lube, and maybe knock off a few of the sharp edges that would otherwise make dealing with it uncomfortable.
Bison Chucks, used to be pretty cheap (Poland, IIRC, possibly several other Eastern Euro Countries as well), for pretty decent goods. Still good, not as cheap as they used to be. Check out KBC Tools and whatever other online catalogs you can find.
Above that, you can spend a LOT on a top quality chuck that still won't magically stop you from having the same bang-your-head-onna-wall experiences as you learn how to get the lathe to do what you expect of it. There IS a learning curve!

I spent a lot of time teaching the stuff before I was retired out of the Forces.
Gonna suggest, if you are new at this stuff, get a used copy of Technology of Machine Tools, by Krar. Check out any used book stores that deal in University Texts, and buy the oldest version (cheapest) that you can find. Great book, lots of How-To info, stuff that has not changed much in the last hundred years, at least, not as far as a guy running a South Bend is concerned!