Some absolutely great Celestion clones are the Southbay Ampworks aka Scumbag speakers. They are accurately recreated pre-rola Celestion clones built to spec by Weber for them. A couple of years ago I did a pile of speaker clips with them (should be still on their site). It originally was a blind test we did for The Gear Page site. They are more expensive than standard Celestions but cheaper than their Heritage series. Well worth their money!
Great Sounds by Southbay Ampworks