I have no money till next month!

The sale ends on the 28th, this Tuesday coming. It finishes 11pm UTC, so that is 6pm EST, in the States.

GOG have several big promo per year.
Usually, old games will be cheaper and cheaper.
According to the prediction of many people here, GOG should have at least one big promo next month.

I'm quite sure there will be another big Christmas-promo.

Why don't they do the promos at the beggining of the month, when people have money?

Because the Black Friday sale is supposed to coincide with actual time of Black Friday? ;)

Hmmm... they could rename it to "Countdown to Black Friday sale ..." :D

And not everyone gets paid at the beginning of the month? ; )

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Anyway, can almost guarantee these will be on sale again before Christmas, so take today's sale price for those titles, sock that amount away, and pick them up at the next sale.

Just to provide a link, folks keep track of the sale dates here in this thread if you want to review it:

https://www.gog.com/forum/general/gog_sales_historical_dates_and_forecasts

Just buy Deus Ex, and get the Witcher 3 at some other time, it will be on sale again eventually (maybe even already in December).
If you can't even afford Deus Ex, you shouldn't be spending money on games anyway.