Skyler is overreacting regarding the expensive bottle most probably because she is afraid of attracting any suspicion regarding their original plan. And you are right; the plan is for Saul to arrange a one-time fixed gambling win to be used as an investment in the car wash, but technically, they are still almost broke.
She is just overly cautious—maybe even slightly paranoid—so she thinks they should not be too flashy or extravagant about their lifestyle. This scene is was quite discussed topic among fans, and usually, there is agreement that it doesn't make so much sense., yet, human brains and emotions can work very strangely in certain circumstances.
For example, in one of the previous episodes, Walt is unnecessarily cautious when Skyler calls him and mentions the car wash over the phone; Walt illogically thinks they should not mention the words 'car wash,' even though they are legally buying it. Some things regarding this topic will also happen in the future, but I don't want to include any spoilers here