there is absolutely nothing wrong with buying products on e-bay...what you are really looking for is what BRAND though.
for a celica shortshifter, you either want to get B&M, TWM, or TRD
. these are by far the best quality shortshifters you can purchase for your car.
buying an off-brand shortshifter very often involves cheap parts, bad instruction manual, and a harder install. look on e-bay for the brands i listed above for the best deal