Welcome to the insanity Baldytop. I use to tell myself (or more accurately, my wife) it was an investment but since I have paid nearly top dollar for everything I bought, not too sure about that. Now the justification is "because I love them and I can".
If my memory serves me right, 1637 was a pretty nice looking Red one on eBay last year. Yes, the parts are getting scarce. Yamiya's replicas are about as close as they come. Buy the replica. When and if the real deal comes along, sell the replica. Forget that last part. Put the replica in storage since you never know when you might need it.
Keith