Trade-ins are tricky. You would almost always be better off selling and buying separately. Especially because dealers will be unlikely to want to pay you money - they'd rather you trade in something cheap for something expensive.
With that said, call around, get an idea of what they might offer, both trade-in and not.
Also, if you bought a brand new $32k car in May, I have a hard time believing it would fetch $30k now, unless it happens to be in high demand. If you bought a used car for $32k in may, perhaps.