If you want them even cheaper injectors buy them from Connaught shaving UK, You get 20 Personna injector blades per magazine and personally I like them just as much as the Schick blades. The Schick blades that come in a pack of 7 are sharp and smooth but are not as sharp as the Personna's, When you get a very sharp blade like the Personna injector blade you give up a little smoothness but they have excellent longevity and are smooth in the milder Schick injector razors IMO.The more you use a Personna injector blade the smoother they become also. The Personna injector magazine is made of plastic and aluminum and are not the best out there but they take a little more fidgeting but are doable.
With US dollar strong the cost are very good even with shipping.
Personna Injector Razor Blades
Connaught Shaving is supplier of quality, traditional shaving products including Wickham 1912 shaving soaps, REX, Merkur & Edwin Jagger safety razors & many brands double edge razor blades. UK Supplier of Feather New Hi-stainless razor blades, Feather Artist Club Razors & Blades & Feather Safety...connaughtshaving.com
The Personnas just don't work well for me; I have much better results with Schicks. As for the keyless Personna magazines that some vendors sell, you can use an empty Schick magazine and reload it with Personnas to enable smoother loading of the razor.