I think you probably came to the wrong place to try and sell this.  Given the typical rate of return on scrypt mining right now, and expected future decreases in profitability, I estimate 50Mh/s will product around 1.9BTC between now and the end of time, if you had the 50Mh/s right now.  Given that these machines in all likelihood will never exist, and even if they are eventually delivered it will not be for quite some time, these preorders at this point are virtually worthless.  AT's forums seem to be filled with the few people still optimistic about AT being able to deliver a working product in a timely fashion, your best bet would be to try and sell it there (assuming AT doesn't delete your posts there).