I'll take a stab at this...
The tractor has the biggest range of dollars. 1960-1970 will run 2-10K Green is the highest by far. I keep an eye out for AC D models. A D14 is bringing 2000-3500 and D17s are running 2500-5000 depending on the series and condition. I think either the D14, D15 or D17 would fit your requirements. If you go newer, the sky is the limit. The new compact NH 4x4s run in the 20-30K range.
You’re going to need a sprayer, tillage device and a broadcast spreader minimum.
I built my sprayer, it's a 60 gallon electric and will cover 6 to 12 foot. I bet I have $300 in it total. You can buy one for an atv for a similar price, but it is going to be about 20-30 gallons, still do-able...
For a broadcaster, you can go three point or an over the shoulder hand crank depending on how ambitious or frugal you are. A new 3pt will run 350-400, a hand crank $25. If you’re planting clover or alfalfa, it could be done with the hand crank, but corn and beans with fert would suck every year...
For tillage, if it is rock and root free, a 3pt tiller is the cats a$$. One pass and your ready for seed. A KK 6' will run 1200-1400. If you have rocks and what not, a KK 7' disc is about 800-1k new.
Nice extras are old planters or grain drills. Large lawn rollers or cultipacs. I see old JD Van Brunt drills popping up at farm auctions, if they have the small seed box on the front, they will plant anything... Clover to corn... I found mine for 475 a few years ago. Parts and manuals are still available.
As far as mowers go, I'm in the market myself, need one before this spring. I've looked at the KK but don't know about the quality, may be someone will chime in. I have also priced 6' Bush Hogs that run 1700ish. I have a Bush Hog lawn mower and it's built like a tank. I have actually mowed standing corn with it no problem.
Alot of these items can be found in the classifieds for better than 1/2 of new. Let us know what you accumulate, it's great fun!