Newegg as well as a few other places have Foxconn ITX systems based on intel h61 and h67 chipsets for around $120+sh, occaisionally under $100 on sale. These systems are all desktop style cases which is ideal for htpc. They include a healthy number of ports incl hdmi and even esata on the back too. There are also some AMD based ones I think, but the intel ones are where it is at IMO.
With one of those, the only thing you are lacking compared to the zacate/atom systems is the cpu, then of course both need HDD and ram. Throw in a G530 or better yet a few bucks more towards a G620 (to step up on the graphics side moreso then processing power) and go from there. If you happen to have a spare drive laying around, you can pretty much have a funtioning system for under $200.
You can also piece it together entirely for about the same. $40-50 for case w/psu, $50 mobo then same as above. Problem is ITX boards are much more limited in selection and are generally about $10 more then equivilant spec'd mATX boards. mATX is very easy to do cheap as there is a bigger selection to choose from. For example if you arent too concerned with tons of ports, you can pick up an ECS H61 mATX board w/hdmi for $30ar from newegg, and a $40 case w/psu and be well under $100 then of course add the above stuff. What I see in those foxconn ITX barebones is besides some of the assembly work being done for you already, if you consider the cost of motherboards with an equivilant load of ports and such, they are actually pretty price competitive too even though you can build something a little more no frills for a little less money.