Summer getaway cards investment?

They may be available, but the price will decline a lot, look at foil cards as an example when they first came out they were about 15-30 now, 1-5. When these summer cards started I saw 1-5, and now .30.

Assuming they don't disappear after the sale is over, save them.

Even if they don't disappear, I think a lot of people will think they will. Consider selling them on the last day at a high markup.

The thought has crossed my mind. I def. was considering buying an entire foil collection and then selling it in a few months for a big profit.

I sell right away usually.

Bad move? Maybe....Not sure I care to much honestly.

Of course they won't disappear, and yes their value will rise.
But is it worth investing in them? Probably not.
You will need to be extremely patient since hundreds, maybe thousands of other people will do the same thing, meaning you compete with too many people, just as you do now. Prices may still rise, but it'll be slow. To make the big bucks, you need to out-wait the majority of your competitors so you can dictate the price.

It'll take years before they have any chance of making you rich.
Thing is, by then most people already stopped caring about cards/badges, and the people that do care, already got theirs ages ago.
The kind of collector that would invest a lot of money, would be immediately discouraged to get into this whole thing when he finds out that there are like 5 badges he will NEVER be able to get(Potato Sack and so on).