I really wasn't kidding when is said in the SE US, that's every bit of a $150,000 job, probably more. Now, I'm trying to suggest work around, that will get him started working. I dont know what part of the world he's in, but if I had to throw out a guess, I'd say, central America. If that's the case, there might be a surplus of cheap labor, and probably a shortage of proper contractors.
When you do much searching, it looks like there's plenty of guys using a Rome disc plow through brush stubble; using 150-200 hp tractor or a D5 sized dozer, and going up from there. Generally, even after that, there's way more trash then you want in a tillage type field, and needs a Ton of raking/discing, and no matter what implements you have; guys on the ground picking roots Now, if we are painting grapes/coffee/citrus or something I'm not familiar with, I have no idea; but a 8 ft planter is not going to fair well with tons of root balls, or even a large amount of 2-3" roots. Pine plantation, is different. Roll that crap into windrows, Rome plow the rest, and plant.
Now; in the bright side; your going to need a good sized tractor for your farm regardless for tillage/planting. See what kind of progress you can make over a week on a 5 acre or 20 acre square. Maybe it goes great, and you keep going, and save $150k, awesome. Maybe it takes 30 days to do 5 acres; and you find out. Remember; if you never F' around, you won't ever find out. Just F' around at a level your comfortable of finding out at. Large implements in the US are often cheap used, because home owners/hobby farmers/"lifestyle" types don't want/need a 2500 pound disc, or a 3 tine deep ripping subsoiler.
Whatever you get; it's going to be min CAT-2 sized 3 point; but don't over look drawbar implements. That can be a lot bigger, heavier, and if used, cheaper.
Another thought; a lot of this forestry clearing stuff is just Heavy steel, but not rocket science. A foresty chopper is basically a 5 ft diameter heavy wheel with blades angled 90 degrees from axle, hooked to a draw bar. Wear and bearings are the only thing to cause problems; and there might be some for bear scrap value. Transporting them, however, maybe a problem.