In 2011 I killed the house batteries that came with our used motorhome by believing the idiot lights and voltmeter (both are overly optimistic for hours after a little charging from the engine while driving. We were in Nanaimo, BC and I bought two deep cycle (not marine) batteries at Costco there. I learned my lesson and got a battery monitor, then a solar panel and these batteries never went below 80% charge. They are still performing very well after 8 years. I see the Grande Prairie, Alberta Costco has the same type of battery a little higher cost than the $90 I paid in 2011.
No problem choosing a size, just measure the length, width and height your battery compartment can handle and take the tape measure with you to the store. And choose the type compatible with the wire connectors you have. $10 back for returning an old battery, not necessarily the same size.