2 important factors
-How mechanically minded/able are you? Like others have mentioned this is key in keeping maintenance costs down and allows you to spend less with older machinery. But 1 other thing to add is how are you set-up now? Do you have a shop or access to one? Any cold storage sheds? Doing all the work on your machines without a shop or even a shed isn't super practical and a decent shop would eat up most of your budget. How about tools? If you don't already have a decently stocked tool chest it isn't hard dropping $10-20,000 to set yourself up by the time you add air tools/compressor/jacks/etc even with shopping sales/deals and getting stuff second hand.
-How much labor do you have? Are you a 1 man show or do you have siblings/children/nephews/uncles to help run machinery? If you have access to spring/fall help you can get 2 or 3 older machines at auction for much less than used 1 mid sized machine. You could have 2 TR97/98s or 2188s with 25ft drapers for under $70,000, add a 600-800bu grain cart for $10-15,000 and $25-35,000 for a semi with a $20,000 trailer and you've got plenty of harvest capacity as long as you have the help to keep everything running.
As for everything else we've bought most of our equipment at auction or privately on Kijiji, keep an eye out for deals and shop smart (know what you want/need and don't hesitate to say no if something looks off). You can pick up a suspended boom sprayer for around $10,000 or a self-propelled for $30-40,000, we've seen several 40ft air drills go for $15-30,000 at auctions the last 2 years with lots of life left, an older 300hp Versy or Case Steiger can be had for under $50,000, find an old Deere 4440-4650 for auger/rolling/baling/etc. Also listen to the guys saying invest in grain storage, getting caught 1 bad/late fall could easily sink you. We've had good look buying old 19ft Westeels for cheap off of the guys putting up the big 30,000+bu bins. Lots of bigger guys would love to clean up their old tight bin yards.
"Though the fig trees have no blossoms, and there are no grapes on the vine. Though the olive crop fails, and the fields lie empty and barren. Though the flocks die in the fields, and the cattle barns lie empty. Yet I will rejoice in the Lord, I will be joyful in the God of my salvation." Habakkuk 3:17-18