You can spend 1000 points for the seasonal badge in the Steam point shop, giving you 100xp. Spending 1000 again will level it up, giving you another 100xp. You can also spend it on other things of course, but those won't give you xp.
100 points can be earned for every 1$ you spend, you might already have some points from past purchases. You can spend 300 of those points by awarding people's contents, such as reviews, workshop mods, screenshots and such, earning you a badge upon giving the first award, with 10xp for every award you give.
Other things to note
All prices will remain the same throughout the entire sale.
Be sure to consult 3rd party stores for steam keys, as Steam itself might not always have the cheapest prices.