In general, go for the random cards through the buy option in the game. Almost all cards are more expensive than 4 hive or 800 sim.
That means that in about 55% of the times you get a card that is worth more than that and quite often 3-4x that.
But if you like to start cheap, than a combination of a park and a wind turbine is an ok start. Those cards are cheaper than 4 hive per card on the market.