"What is meant by были альтернативными?"

It's a term "альтернативная сделка с недвижимостью": Что такое альтернативная сделка (альтернативная продажа)?
You sell one property and immediately buy another one. Buying is chained with selling, so, you need relatively small amount of money to fill gap of values.

"А на таком рынке немного другие законы, поскольку "чистого" рынка фактически нет."
Such a market has some changes in it's laws, because it is not actually a free/real market.

After USSR's strongly administrative economic system it's cliche to say about "free market" in publications.
That is, imho, these conclusions of this article is pure bullshit.
It IS free market as is. But author wants to find something different guilty in 'bad pricing'. 'Free market' still is 'golden cow' for him.
"Here will come free market and everyone will be happy. If everyone are not happy - it is not free market' post-soviet bullshit.