Hmm. I'm not sure whether this will the the right answer or not. You've not stated where you've come across the term 'standard HCI models'. If was referring to mobile phones, hard drives, mp3 players, plasma TVs or something that I've not even considered, my answer might be totally inappropriate. If, however, it refers to PCs, then this might be what you're looking for:
In order to get computers into more homes (particularly into the homes of people on low incomes) the Government came up with an idea known as 'Home Computer Initiatives'. This was a scheme, supported by BT, Intel and Microsoft, under which employers were offered tax beaks so that their employees could obtain home computers at significant discounts.
The computers offered under this scheme were usually fairly basic models. (e.g. with on-board sound and graphics). If someone is now selling PCs described as 'standard HCI models' these will be good quality, but fairly basic, computers designed for general home use.
It should be noted that the Home Computer Iniative tax breaks were abolished in this year's budget. This may have left suppliers with stocks which only seemed attractive when offered with the discount which the government effectively gave to users. This forces the suppliers to offer equivalent, or even greater, discounts themselves, in order to clear their stocks.
Chris