Not to be discouraging, but you may have trouble finding a complete three spoke wheel in decent condition within the budget you described. I regularly buy GT wheels as cores for my steering wheel recovery service, and the going rate on ebay and here on the forum is around $50-60 for a wheel with damaged leather and rusty/tarnished spokes (wheels in good condition often go for double that). I'm not saying you won't find one, but you may be looking for a while until you stumble upon a good deal. If I come across anything, I'll be sure to let you know.
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"The Twins"
'87 GT 3.4 pushrod daily driver *SOLD*
'88 GT 3.4 DOHC
'88 T-Top coupe DOHC swap in progress