I'd say Rainbows have certainly seen a resurgence in recent years, likely driven by some of the crazy high values in other sports Prizm parallels, the chase for short print run rookie parallels has grown to incredible levels.  When I started my player PC's some of these variations /10 or 1/1 were pricy, then over time the lustre seemed to fade and something out of 10 just didn't seem that rare.  I think we're back to popularity, for me the rainbows I have are ones that I got through my player collecting, and I couldn't bear to break up when I sifted out those PC's.  I think I still need 1 or 2 Havlats from that Artifacts year, but I was really happy with what I did get together with 7 1/1's.  The Prizm cards are a bit of a force fit onto this page as I haven't decided if I'm keeping or moving those.