I haven't seen them, but it is possible there are still points where the plastic touches that water can't evaporate away.
So, Even if you get these, I suggest you first thoroughly dry out your blades if you aren't going back on the ice again in a few minutes. And oil or grease them if you aren't going to skate again within a day or two. Especially if your blades aren't stainless steel.
With the $8-10 ordinary plastic blade guards, many pro shops cut them and mount the springs for free, if you buy the guards there.
You don't need skate guards in your car or at home. I take off my skates, dry them, then carry them upside down by the blades (it is important to keep the mounting screws fairly tight). But I use plastic guards if I have to leave the ice for a few minutes, or if I leave my shoes in my car, so I need to walk in my skates on a parking lot.
My favorite guards were cut from leather, by Don Giese. Very simple design - just folded leather, with bungee cords threaded through holes in the ends. Easy to fold again and fit in a pocket. (I have one jacket with extra large pockets I can just barely fit normal plastic skate guards in, but it is a bit awkward to move in like that.) I didn't feel I could walk on them over a gravel parking lot, but otherwise they were pretty durable. Would be easy to make something like that yourself, though leather isn't cheap, and I don't think that Leatherette is as tough.
I considered the "roller guards", but they were $50 or $60, and a lot of people said they broke easily. Besides, they didn't really turn your skates into inline or quad roller skates - there were two closely spaced wheels at front, and at back.