One only? There's no way.

For general purpose... a high-end yamaha midi-capable piano, several professional soundfont cds, and a good computer. That'd probably be $10k-15k right there.

For personal pleasure in playing... a double (F/Bb) horn and a good gold-plated flute. Around $4000 for both.

But right now, I'd be happy just to have a midi-capable keyboard with touch-sensitive and full-size keys.