I have the same problem with my 94 ST. The local Memphis dealer said the parts are called stays and cost $157 ea. Try liftsupportsdepot.com (ebay seller - $57) and CSK / partsamerica.com ($20 ea). I think I am going to buy some from CSK.
2000 celica struts toyota PN: 68960-80063, and 68950-0108 and list for $127.41 each.
however i gave you the strut number for the Celica with rear spoiler, and rear wiper, so they should have the strongest rebound force and therefore should support whatever configuration you have, especially if you're sans wiper or spoiler or both.