Coincidentally, we DID have $50,000 to spend this fall, and we spent it on drainage. In the midwest, clay soils, some flood plain, no question.
As to trees, if you can't move in big machines, the best folks in Chicago are about $2400 per day, and they can do a lot of trimming, or hack down maybe a couple oak trees in that time.
If you don't care how much of a mess is made on your golf course, Homer Tree Service is the way to go for big jobs. We originally figured something like $120,000 and six weeks to do all the tree work for our golf course renovation, but Homer cost 1/3 of that, and did it in a week. Huge machines take down an Oak in maybe 20 minutes, the grind everything into big piles of sawdust. We got some amazing pictures, which have never seen the light of day.