So it's an HP thin client box running XP embedded. HP T5730/T5740?
HP T5730/T5740 - $60-$90, could be cheaper can buy these in bulk.
Amiga Forever Plus - $30
AmigaOS 4.1 FE - $28
WHDLoad - $30
Amiga Joystick to USB Adapter - $19
HDMI Cable - $5
Total - $172-$202
D-UAE -
$215 In the USA
$275 Internationally
So not a bad deal :-)