Agüimes is one of the easiest Gran Canaria municipalities to do cheaply because most of its anchors are free: the casco histórico, the San José church, the miradors above the ravines, and the trailheads into Barranco de Guayadeque all cost nothing. The decision that moves your daily total the most is where you sleep — inland holiday apartments and rural casas in the old town and surrounding villages routinely undercut beachfront resorts by 30–50% while keeping you within a 15–25 minute drive of the coast.
Your other big cost lever is food rhythm. Eating a light mid-day menu at a guachinche or local bar (set lunch menus are the cheapest legal meal of the day) and a late, smaller dinner after 9pm is both budget-smart and culturally correct. Add the Global guagua bus for airport transfers and inter-town hops instead of taxis, and you can comfortably stay under $100/day as long as you avoid peak Carnival weeks and August resort surcharges.