What is the cheapest visa to move to Portugal?

Short answer: The D7 is usually cheapest if you have passive income — the minimum threshold sits around €870/month.

Government fees aside (€90 visa + ~€170 AIMA card), the D7 has the lowest income floor (1× IAS for the applicant, 50% for each dependent). The D8 demands ~4× minimum wage. The D4 student route doesn't have an income test but requires scholarship or savings proof. Run Visa Advisor to see what your budget supports.