As a buyer, you're in agood position. Prices are so low because the whole organ market went into nose dive a few years ago. Spinets are being given away or sold for pennies, but consoles command a slightly higher price, if only because many potential buyers want to gut them and use them to play software based organs.
The spares issue is common to many instruments. If a bespoke part fails, it's often a case of buying another instrument and playing cannibal. Some parts are still around, and you'll find links to people like Organ Service Co and W D Greenhill here in many threads.
I used to have a 652 and I think it's a great sounding organ. Not quite the vintage Conn sound, perhaps, but a really rich one. Again, it's theatre based, but it can make a fair old straight sound, Nice percussions on it and a very handy transposer if you should ever want one!
Andy
It's not what you play, it's not how you play. It's the fact that you're playing that counts.