From Elise FAQ
Don't pay the dealers over the odds for simple service parts. Many are borrowed from other much cheaper cars. These part numbers are definate for the S1, if you know them to be correct for the S2 please let us know.
Wishbone end balljoints
QH part number QSJ883S
Track rod end balljoints
QH part number QR2382S First Line FTR 4212 AP Lockheed (also known as Delphi)TA1498 GSJ 732 (UNIPART)
QH Part number QWB661 Timkin part number JRM3938A (OEM part)
Available from any decent motor factors.