The slowest 286 ran an at 6 MHz not 4.77. Check it out.
I'm also pretty sure the 1.2 MB FDD came along quite a bit later.
According to csgnetworks.com (and they've been in business THAT long), the 1.2 MB 5.25" drive came out in 1978, while the 720 KB 3.5" drive came out in 1980 and the 1.4 MB 3.5" drive came out in 1984. IIRC, the 3.5" drives as well as the 1.2 MB 5.25 drive were not exactly standard equipment on PCs until the 386s were introduced in 1985. In any case, it's a far cry from what $6,000 would get you today.
As for the speed, the 286s ran up to 20 MHz. I know that the initial launch in 1982 covered 6, 8, 10 and 12 MHz, but I haven't been able to find out when the 16 and 20 MHz models came out. However, I'd have to say that both were available by 1984.
My memory is a bit hazy on prices, but I think that $6,000 would have gotten a 286-12, 640KB RAM, a pair of 360 KB drives, and CGA color graphics.