UMPCs can't be priced at US$500 at this time
I have been using my Samsung Q1 extensively the past few months and absolutely love the small slate form factor Tablet PC. I paid US$1,100 for the device and then added 1GB of RAM for another US$80 and still think to this day that I paid a good price for a powerful device since it meets so many of my needs in a small form factor. Linda Epstein from TabletPC2.com posted an article on why the desired US$500 price Microsoft envisioned is not realistic for Origami/UMPC devices at this time.
As Linda points out, it seems that many people complain about the UMPC prices because they compare these devices to low cost laptops where you can get a Dell for something like US$500. She then goes on to offer a detailed comparison of the actual specs and finds that the US$500 Dell laptop isn't priced as low as once thought compared to a UMPC. The UMPC form factor is also considerably different than a laptop making it a much more portable system. A very detailed breakdown of the current manufacturing costs of a UMPC is presented showing that estimated costs alone exceed around US$700.
I considered an OQO device at one time, but at US$2,000 that was just too much for me to swallow. Then when I saw the UMPCs coming in at US$900 to US$1,100 I started looking into what they could do for me since laptops with the same specs cost about this price. I helped justify the initial purchase because of the multiple functions the Samsung Q1 could satisfy. It is an excellent portable media center device (stand alone PMCs cost US$300+), in-car GPS system (compared to US$700+ for many units), Tablet PC (most Tablet PCs run over US$1,200), and eBook reader (Sony's upcoming model will retail between US$300 to US$400). The Samsung Q1 also does much more since it is a full Windows XP computer with a 40GB hard drive and 1GB RAM, but as you can see it can fill many roles and actually is a good value for the money. If you can't afford one now, like all technology the price will drop in a few months and maybe you will find one at a lower cost in time for Christmas.