Welcome to the club and congrats on your purchase. We are also from Ontario. What part of Ontario are you from. With regards to the holding tank, you make want to check out replacement ones from
Icon Direct This company is located in Manitoba and they have been great to deal with. One thing to consider when dealing with companies in the US vs ones in Canada is that you must factor in the cost a courier will charge you for clearing the items into Canada. UPS is one of the highest customs clearing fees I have run into.
Now depending on where you are located in Ontario, if in Southern Ontario, you may want to consider a trip to Elkhart IN and visit the RV outlet stores to pickup the supplies you need. Two of the best outlet stores I have found for both price and selection are
Bontragers Surplus
Johnsons RV Surplus
By the way I should mention we love to see pictures of everyones trailer. When you get a chance, please do post pictures of your trailer.