Peru works best when you land between the rains and the crowds. By mid-May the Andes trails dry out, the Sacred Valley goes green, and you still beat the July-August crush. You will want Cusco for acclimation, two or three days on the Inca Trail or the Salkantay route to Machu Picchu, and a stretch on the coast around Lima and Paracas. Add up flights, a mid-range hotel, guides, the trail permit, and food, and a two-week trip for two usually lands near $4,600.
Most people do not have that sitting in checking. The move is to put the whole trip on one purchase so the bill lands at once, then pay it down on a steady monthly schedule. One US card lets you spread a balance across 18 months with no interest during that window, which turns a $4,600 spring trip into about $255 a month for a year and a half.
The 18-month window is a deadline, not a free trip. If the balance is still on the card when month 19 hits, interest starts accruing on whatever is left at the card's regular rate, and that can quickly cost more than the flights did. Pay it off before the intro period ends or be ready to refinance the balance onto another promo card before the clock runs out.