JayKallaAmazon is probably the best place to get blades. Standard says their razor is designed for Astra blades, you can buy 100 blades for ~$10, shipped. If you want really in depth discussion of blades-razor combos check out badgerandblade.com
tiguansmYou can use whatever you like! I just got mine and my first shave was with a dorco blade. It was really excellent. "Designed for Astra" just means they optimized the shave while using an astra blade; it is compatible with any standard blade.