The cheapest way that I’m aware of is to always start with the smallest property, like a bachelor suite and pay that off quickly to create a bigger downpayment and buy and sell something a bit bigger, like a 1 bedroom apartment and keep moving up until you can buy a home.
Reduce Zoning and building requirements.
They add 10’s of thousands of dollars to the cost.
These young people who are starting out with tiny homes actually are doing just that, except being kinda extreme about it.
A young individual or couple would do well to minimize and start with the smallest home they could pay off in five years, and go from there. If they live and work in a big city where that's not plausible, that is their choice.
DON'T let the REALTORS, MORTGAGE LOAN BROKERS, or RELATIVES goad you into the conformity of a big house you can't afford. ("But LOOK at the money you'll save on your TAXES!!" - This is a lie.)