I have four Amazon gift certificates worth $25 each, for a total of $100. You may redeem unlimited gift certificates on an Amazon order, so you can use them all at once or space them out. They do not expire. I am looking to get $90 for these. I need new brakes on my Xterra, and strangely the brake shop refuses to be paid in Amazon gift certificates If anyone plans to spend money on Amazon, this is an easy 10% off! No mailing necessary, you send payment by PayPal and I send the gift certificate codes.