I would like some suggestions for some of the top notch funk groups to buy on CD

AWB (average white band)
Con funk shun

These would be the best CDs, specifically, to begin with:

In Yo' Face, vols 1-5. Excellent introduction to funk across all the bands mentioned in previous answers. Provides a good overview so you can find out who your favorites are.

"Funk is its own reward" - George Clinton

Parliment Funkadelic.
Hot Chocolate.
The Commodores.
The Dazz Band
Zapp featuring Roger Troutman.

Sly & The Family Stone
The Ohio Players
Bloodstone
Frankie Beverly & Maze
Eric Burdon & War
Skyy
Starpoint

parliament
george clinton
bootsy collins
the gap band,etc

those are all my favorites

Stevie Wonder, The Brothers Johnson, Earth, Wind & Fire, Bootsy's Rubber Band, Tower of Power, Ohio Players, The Commodores, Kool & the Gang, Confunkshun, Slave, Cameo, the Bar-Kays, Zapp, the Gap Band, the Dazz Band, James Brown, the Average White Band, Wilson Pickett, Parliament, Funkadelic, George Clinton, Sly & the Family Stone, Lakeside, War, Rick James, and many more.....