Sorry... it's just a dumb idea, plain and simple. One of the MAIN reasons for putting glass or plexi over anything... ready? ... TO PROTECT IT!!!!
Leaving the mats and the print bare to the world is asking for trouble. The mats will tend to bow out away from the image due to changes in humidity... the glass or plexi will keep the whole package tight and looking professional. The mats will also get dirty as will the image.
Nothing screams amateur more than having your work half finished. The other thing that screams it almost as much is polystyrene. Wait... one more thing that at least murmurs amateur is having frames on your art that do not work with the art because you got a bargain on them.
Nothing turns customers off more than poor presentation of the art.
Stop being so cheap. You saved a bunch of money on the frames at a clearance sale, so just go buy the glass and get it over with.
If you plan to sell these, then you will sell more when they are completed. No way I would buy anything in a frame without glass as you suggest as I know that I would have to spend time and money opening the package up to put glass in.
Without glass to protect the package, you will quickly scuff or scratch or outright damage it every time you have to transport it.
For peterAlt... funny that you say that you get lots of compliments on how it looks, yet you then go on to say that your buyers "tend" to want glass or lucite on the art before they buy it.
You seem to like making more work for yourself. You'd rather make another print (and mats) if it gets damaged instead of protecting it in the first place and you'd rather show your work unglassed and then have to open the frame up and put the glass in because most of your customers prefer it that way rather than putting the glass in to begin with.