I think you will have a tough time with anything less than 4 digits (for a pair) that would even come close to those old Advents. I had to part with my old utilities a couple years ago as they played havock with my new TV screen.
So I got a "cheap" surround speaker system that sounds surprisingly good, for what I paid for it, half price at $450.
However, I found that even though it seemed to have decent bass, not nearly as impressive as my old Advents. So I bought a good sub ( Athena AS-P6000) and I can hear the low 20htz note on ELP's Lucky Man again.
I would recommend you looking at a decent set of smaller bookshelves and get a good sub, as it will make the loss of the Advents easier to take.
I feel your pain
Colin