Seriously though, without knowing the person and what they've done to the Supra already it's hard to say.
For example, they may be an HKS fanboy and we tell you to get an Apexi part, or maybe they just replaced the brake lines but we tell you to get brake lines...
Toyota goodies are always nice though. A nice
TRD shift knob or a TRD oil cap
(and an ove glove to go with it in case it needs to come off while the engine is hot)
Tint is good too.
The list could go on and on and on. And we'd probably mention things this Supra owner already has.