Board Game Arena

When you're buying a card from the line up, it zeros out your gold, so if you had additional buys, you can't actually purchase anything. It needs to be reset to income so you're not losing out on actions. https://boardgamearena.com/6/spacebase?table=273061436 See log for what the gold was doing. What was really weird was that it wasn't zero'd out when I purchased a endgame card, only from the main line up.

From the manual: "If you buy a card you must spend all of your gold (set your yellow cube to 0) even if that means you
spend more than the price of the card."

You have to do the additional buys before the main buy. This does mean that sometimes you have to wait a turn to get the additional buy (or just activate the ability for the side-benefit and then skip the additional buy because you have no money).