My sister, my niece and I are in a scrap challenge. We have challenged ourselves to make 100 items before we buy anything new. We are permitted to buy adhesives, blades for trimmers or cutters, etc., but nothing else. We also are permitted to print photos. We've been doing this for years and always start on January 1st. Sometimes it takes us 6-8 weeks, sometimes it takes us months, but it always makes us look at our stash with a more creative vision.
I usually give myself a little added bonus in that I assign each layout or card a price ($1/card and $5/layout) as money that I can spend later. I don't always use it, but it's fun to add it up.
What this challenge does for us is make us more mindful spenders when we do finish our challenge and are permitted to buy again.