Is he a collector of scotch or is he a scotch drinker?
There is a bit of a difference and the answer will change my answer.
For a collector I would recommend a rarer bottle, whereas for a drinker I would suggest a well known luxury bottle.
For a scotch collector:
-Balvenie 21 Portwood Finish.
-Highland Park 18 or 21 (the 25 is like $220 but better).
-Glenlivet 25 (although I'm not a fan of glenlivet).
Pretty much any scotch over 18 that you can find in your range will be pretty good. But you may want to scout out some stores in your area to see what they have. And if you'd like, you could post the results up here and get votes on the best option.
For a scotch drinker but not collector:
-Johnnie Walker Blue Label
-Chivas Regal 21 Salute or 25 yr.
Also, I don't mean to overstep, but if your friend is going to be looking at chemo-therapy or other cancer treatments then maybe scotch isn't the best fit right at this time. I'm not really sure what the relation between drinking and cancer therapy is, so it may be worth a little research. Think of what his other passions in life are and maybe a gift regarding that will equally lift his spirits.