Economical full-range floor-standing speaker options?

Yes, Salk’s are awesome!  Salks finishes are really cool.  They tend to look even better in person too.  Long wait times though.  I haven’t heard the song 3’s but with those drivers and cabinet size I’m sure they sound damn good.  My speakers use the same tweeter, same with Hilde45.  Its a pretty sweet sounding tweeter.  Theres a pair of preowned SS6M’s for sale right now too that you might look at...

I’d consider a pair of preowned Joseph Audio Pearls too if you could swing it.  Every time I’ve heard them they sounded fantastic and everyone else in the room agreed.  

Salk speakers are interesting. Their response curves are cut off at 200 Hz. Nothing bellow. Disturbing. They use good drivers. Their cabinets look great but there is a problem. They radius the corners and wrap the veneer around the corner. The veneer is only 1/64" thick and is on MDF. MDF is hardest on its faces but much softer in the middle. You can easily see this on a cleanly cut edge. When its edges are radiused it exposes the soft interior which now forms the corner which is the part of the enclosure most susceptible to damage. Although they are using a polyester finish which is the toughest, corners always take a beating. The corners should be made out of solid wood but it is difficult and time consuming to match grain and color. IMHO this is a bad shortcut to take. There is no good way to repair a damaged veneer corner and because the MDF below is a different color and usually lighter it will stick out like a sore thumb.  If you get these speakers make sure NOBODY goes near them. One wrack with a vacuum cleaner is all it takes.  
If I were making those enclosures I would use a very hard contrasting wood like Ebony (Black) or Maple(white) in the corners. Veneer is fine for flat surfaces but bad news on edges. I would also make them out of plywood not MDF. Many do not realize this but plywood is stiffer than MDF. How do I know these speakers are MDF. You can not radius plywood and veneer it. Plus good cabinet grade plywood is 3-4 times the cost.

“Salk speakers are interesting. Their response curves are cut off at 200 Hz. Nothing bellow. Disturbing”

Huh?  Are you saying that Salks don’t produce sound under 200hz?

Lots of great suggestions above.  In addition, I see a set of PBN XPS https://www.audiogon.com/listings/lisa7j1e-pbn-audio-xps-full-range and this Goldmund https://www.audiogon.com/listings/lis9j37f-goldmund-super-dialogue-full-range that likely, in either case, would be all you would ever need.   This also might fit the bill:  https://www.usaudiomart.com/details/649541523-atc-scm40-v2-original-owner-pristine/images/2351151/.  Else, also consider Revel, Aerial, larger ProAcs, and the nice JBL stuff.  

+1 on the ATC SCM40v2.  Another member just bought a pair of those based on my recommendation.  ATC is awesome!  Possibly the most overbuilt drivers in hifi