Without more info, we can't help. 3200 miles on a Kat is nothing, unless the bike has been wrecked or abused.
You NEED to find out what he means by "slipping"; does the bike run and shift OK, but the clutch slips on acceleration (revs rise but the bike doesn't go any faster) or does the bike POP out of gear or not shift properly (false neutrals) when shifted and power is applied.
The first is caused by poor clutch ajustement ( $0 ), or a fried clutch (a couple hundred bucks);
The latter can be caused by a. Stuck shift detent mechanism ($100 or so) b. bent shift forks (couple hundred) c. damaged gears or dogs (many hundreds, depending on if busted parts have been floating around doing other damage.)
If the bike shifts poorly (stiffly) because the clutch is dragging (and with that few miles, it has sat a LOT and may be munged up), it may be simply a case of sit-itus,; fixed with an oil change and a little riding.
YOU NEED MORE INFO>>>>>