I attended SRAP in the summer after my junior year (2013), and, I must say, it was one of the best experiences of my life (not exaggerating). I believe application process involved test scores, an essay, and letters of rec. When/if you got in, you have to fill out quite a bit of paperwork, but it was all worth it. They paid for room and board, and I made $2000 (!!!). Plus there were weekend excursions to Denver (we stayed at a hotel overnight and went to the zoo and aquarium at no cost to us; they handled food too!) and a hiking trip in the mountains (got to see snow in summer). Evenings and weekends are your free time (I suggest exploring Laramie), and I still remain good/great friends with my fellow SRAPers to this day (they also went to some of the best schools in the nation, such as Yale, MIT, and Stanford; I attend UF on a full scholarship). You work/research 8 hours a day, 5 days a week, but the strenuousness of that schedule really depends on your research mentor. In the end, I wrote a 15-page paper and gave a presentation in front of fifty people. A great, relatively obscure program that pays both financially, academically, socially, and experientially!
Literally, you pay for only the flight there and back, and any personal expenses beyond the meal plan food they provide.