Yes it's heavy.....but it's a LOT lighter than it would be if it were solid, or made of wood.
You can buy the putty at business supply stores like Staples or Grand & Toy. It usually comes in white or blue....but DON'T buy anything but the white kind. (I had a client rent the stand and she used blue putty to stick on the ribbon. The stand was outdoors in the sun/heat for nearly a whole day and the blue putty actually stained my stand. I had to re-paint the whole thing after I tried to get the marks off with a Mr.Clean Magic Eraser and it didn't work.
One pack of putty lasts me about a year. All you need to stick the ribbon on is a tiny flat piece of putty (about the size of a dime) every foot or so.
A pack of the putty is about $2-$3
As for the type of ribbon that's best, one that's a bit thicker....like grosgrain ribbon. Satin is pretty, but you can see the bumps of the putty through it. Chiffon ribbon is worse, because it's translucent. Wired ribbon is really hard to work with evenly so avoid that. I liked using a grosgrain ribbon of about 1.5"-2" in width.