Honestly if you’re looking for soundstage in a bookshelf, I can 100% recommend GR Research NX-Studios. Not saying this as a GR kool-aid drinker, but just knowing what I’ve heard they are phenomenal at any price point, let alone right in your budget, and fantastic customer service as well. They might lean a little neutral when built with Sonicaps throughout, but toss in something of copper caps for the tweeter circuit and you’ll be sitting pretty for one hell of a nice speaker. You can now get them prefab in your choice of finish for your budget, or go DIY for a couple thousand in savings. But quite literally they are THE best imaging/soundstaging bookshelf I have ever heard, even in my small 12x10 listening room. Side to side pinpoint imaging as well as front to back layering are all easily discernable, but something you won’t get with others is height. Easy example is Bob Marley’s Redemption Song have the acoustic guitar directly in front between the woofers, but Bob’s voice clearly 3ft higher and slightly farther back. Spooky good.
I will say, with good bookshelf speakers should come a (or a couple) good subwoofers. So much of the fundamentals of soundstage come in room acoustics below 50hz that you’ll want some help there. A Rythmik or REL should mate nicely if you didn’t already have something. Used market maybe $500 for something decent.
Demo options are less than others as you’d rely on someone opening their home for a listening session, but a couple posts here or over on Audiocircle and I’m sure you’d find someone within a short drive. Heck, if you’re near Portland, swing on by for an afternoon.
Just my $0.02 as a bookshelf speaker fan.
-Lloyd