speaker upgrade

group,
after cobbling up a sytem 2 years ago that would just get me going, i am looking to upgrade speakers. i assembled the parts express
BR-1 kit which is driven by an audio refinement complete integrated amplifier. no fancy cabling and i am currently using a sony dvd player as a source. i would like a speaker that mates well with my current amplifier and would allow me to justify the additional expenses of upgrading ancillary components and source. i am looking for a bookshelf design and am willing to spend $500 +/- $100. prefer used and diy (need pre-assembled cabinets though) is fine too (value is king).

room is about 15' X 17', speakers arranged on long wall, hardwood floors (concrete underneath) with area rug in front and typical living room furniture. placement of speakers into the room is not a problem (currently they are 36" from rear wall).

i listen to all types of music except country. jazz, funk, pop, hip-hop, electronica, rock, and some classical make up the majority of my listening preferences.

some speakers that have caught my attention:
quad 12L (used)
von schweikert VR1 (used)
ed frias AR.com diy kit

would like something a bit more refined than the BR-1s. the amount of bass from BR-1s is sufficient, but would like it a little tighter, taut. clean mid-range and non-fatiguing highs also important.

thanks for reading. any comments/help is greatly appreciated.

best regards,
johnny5