Call me cheap, but I prefer to go to the local dollar store/dollar general type store and pick up the cheap knives from there, grind/smooth down the blade back to blank stock dull and work with those. They are already in the proper shape, they have the right feel and THEY ARE CHEAP so that if one gets lost or broken who cares.
Sometimes I think the specialty market of 'training equiptment' can, at times, be enticing but a waste of money spending.
If you are dead set on purchasing a trainer, I still say buying blade blanks is the way to go. THe wt. is real and the shapes are real as well BUT there are no edges/points to worry about. You generally can get them in volume relatively cheap. If you have any machine shop/school shop teacher connections, you might be able to get them to make them cheaper than you can if you try to order them as well.