Markets go up, markets go down and even the smartest experts can't accurately predict when a market will peak or bottom out. If you're buying a home as a long-term investment (and for long-term enjoyment), you should be protected from short-term changes in the market. Pick a home that meets the needs of you and your family. Then you'll enjoy living in your investment as it grows in value.
The sale of the severed portion of vacant land would not be subject to GST/HST since it is not capital property used primarily (more than 50%) in a business and it is not being sold in the course of a business. However, if the land was subdivided into more than two parts, sales of the severed portions are not exempt unless the portion is sold to a relative (or to a former spouse or common-law partner) for their personal use.