So you want something that you just touch up your knives on, or do you want a system that you can reprofile the edge and change the angle and to sharpen butter knife dull knives?
If you keep up on knives and don't let them get dull you can get away with just touching them up the majority of the time.
The strop can be as simple as a scrap piece of leather from a belt or a store that sells leather or a piece of MDF or even a piece of cardboard from the back of a legal pad. You can also buy a nice premade strop that has fancy wood and a nice piece of hard leather. The compound you put on the strop is the key, for me at least. I didn't have any luck with Sears green chromium oxide (which isn't that high quality) and I think I actually made some of my knives more dull. With today's 'super steels' which are hard and have lots of carbides, I suggest diamond spray which is harder than the carbides and effectively cuts the steel. Since getting my 1 and 0.5 micron diamond spray I have been able to just strop my knives back to scary sharp when they start to lose their great edge. This is once or twice a week on ZDP and M4 which hold an edge for a long time. I haven't had to actually sharpen a knife that gets this treatment in a long time.