Refurbished ones are just as good as fresh ones, and basically always "on sale" since their price is reduced.
Valve seems to be moving towards a very likely Steam Deck Refresh. Very little is known about when or how this will happen. Based on previous comments and data-mining, the refresh will have the exact same amount of gaming-power. It may, however, have a better WiFi-chip, better screen, and stuff like that. Nothing is certain and if you want a Deck soon-ish, I wouldn’t recommend waiting for this.