How about a cheap folding machine or file server :
US CPU prices today look realistic even compared to the mainland China consumer market.
The cheapest Core 2 Duo 6300 clocked at 1.86GHz LGA 775 Processor retail will cost only $183 retail. This boy can be heavily overclocked even with air cooling, some say to 2.6GHz or beyond.
But compared to other deals this is ultra expensive. You can get an Intel Celeron D 326 Prescott 2.53GHz LGA 775 for $47 only. This baby will be significantly slower but it is a quarter the price of a Core 2 Duo