However, some would argue that a pair of bookshelves plus a decent sub would do a great job for 2 channel music system. Yet, some even say that you would need a sub even if you have floorstanders.

Do you mean 3k to 5K including the electronics, or just the speakers?

Axiom M60s, QS4s, VP100 Onkyo TX-SR804 Oppo 970HD Rotel RB-1080/RCD-1072 REL Q150E sub, PS 3