Crazy. I picked up The Colour of Spring on vinyl like a month ago for $8.
First, my hat's off to you for mentioning Talk Talk first, very nice. I totally agree. They made some nice synth-pop in the 80s, then produced two unique albums at the tail end of their career that had almost nothing to do with anything that came before - and one of those, Laughing Stock, is a masterpiece IMO. Absolutely love that album.
I quoted what you said here because The Colour of Spring is not hard at all to find on vinyl. Laughing Stock is very difficult to get, probably because it was released when vinyl was already considered obsolete (hehe), and was never destined to have a wide audience. It's not necessarily $220 hard-to-find, but I recall seeing it go for a lot on ebay, and that was years ago. Man I wish I had a copy.
I did pick up a vinyl copy of Spirit of Eden in Germany, but it's not in the best condition, and I didn't realize til after I bought it that someone had written on the back of the cover, something to the effect of "Dear so-and-so, I hope when you listen to this you will always think back on your visit with us in Frankfurt."
Anyway, here's some ever-improving bands I can think of off the top of my head:
The Church - This Australian band started in the early eighties, they remain prolific and have released more amazing albums in the last ten years than most bands do in their entire careers. The solo output of Steve Kilbey, the bass player/singer of The Church, also continues to get better and better.
Radiohead - This has already been mentioned many times in this thread, but I agree that they've gotten progressively better, I listen to their later albums more than any of the others these days. Thought I was the only one!
New Order - Again, I listen to their last two albums more than the older ones. It always amazes me when a band this old can manage to put out such excellent material.
As someone with a Robert Smith silhouette tattoo on my leg, I'm sorry to say I think their best years were behind them after 1996. Not happy with the last two albums...