GST applies to a newly constructed property's purchase price the way it does not to a resale home, so factor that into the offer on anything built new rather than bought as an existing rental. Resale investment properties carry no GST, only the usual closing costs.
If your mortgage requires CMHC, Sagen or Canada Guaranty insurance, Saskatchewan charges provincial sales tax on that premium at closing, and your lawyer includes it in the final statement of adjustments alongside legal fees, typically $800 to $1,500, and any prorated property tax.
None of this changes annually with the market, only with the property and how it is financed. Get your hand-reviewed valuation from Joel Dyck.