First... If it IS a ford 1510.. then it is a ford.. Shib.. just made either the engine ( or the whole tractor for some models.. etc ). All the NH's right now are shib's.. etc.
Like you've heard.. your price ranges as follows.... new 'big three' domestic models will be the highest price, and more or less best parts / labor support via the dealer.
Used domestic models range from almost new to cheap.. depends on model and condition.
Antiques fall in that category too. Sometimes you can pick up a deal on older iron. Just depends on what your uses are.
Older iron ranges from -no- parts / dealer support to fairly decent support depending ont he make / model.
For instance.. ford N models have excelent parts support, while some of the orphan model tractors have next to nothing.
Then comes grey market tractors. Also lots of hp per dolalr compaired to domestic units. Depending on the model, I believe many were ahead of their time in engineering.. for instance.. Yanmar.. good tractors..
Parts support is a bit soft on the grey's. Many dealers that support similar domestic models turn a blind eye to the grey's. For example.. there were domestic model yanmars.. and it is common knowledge that JD compacts use yanmar engines... even so.. Don't think you will walk into a JD store and ask for parts for your grey yanmar.. they'll laugh. Same with Kubota grey units...
If you buy grey.. research the model, see if there are dealers to get parts from, and check to see if there are any special problems with that model.. for instance.. some of the smaller yanmar 4wd models are very hard to get front drive parts for...
Next would be imported units for our us market.. like the korean models, indian models, and chineese. ( Mahindra, Jinma.. etc )
The indian mahindra are solid.. very IH / case in appearance.. though are priced almost as high as domestic models.
Jinma is chineese.. and while I feel their technology is still inferior to well.. most everybodies else's tractors.. they have finally reached a usefull level ( in my opinion ). Their fit / finish leaves a bit to be desired, and it has been talked about that many of thier fasteners / nuts / bolts might need to be replaced, etc. Their castings do not have as good metalurgy.. so are bigger to make up for it... these are all trade-offs, though, as the price makes them attractoive. For instance.. a 20hp jinma is in the 3000 dollar range.. depending ont he dealer.. there may be some warranty with that too.. For non-commercial light / medium duty work.. I wouldn't mind a jinma. I've test drove a few, and figure if I ever need another small new tractor, they will get an honest chance in my purchase plans.
As with ANY tractor.. foreigh or domestic. Don't just look at the hours... While it is a good indication of time in use.. it doesn't show maintenance and care... the tractor itself will be self evident.
Look for repairs.. are they shoddy bandaid repairs, or functional repairs.. or good repairs.
Does it leak ( almost all tractors will drip a drop here and there.. no big deal ).. it is the ones where the engine is black shinny and gritty / dusty that you worry about.
Look for things that are about to fail.. and figure what they will cost to replace. For instance.. if a rear tire is flat / or bald.. figure what it will cost you to replace. For instance.. a 16.9-24 big flotation turf tire and tube runs around $480 installed..
Also beware of steam clean or fresh paint jobs... fresh paint hides alot of things.
Look at the air filter, or oil bath for the air filter. Look at the engine oil.. see if it is low... ( if it is .. chances are that is how the previous owner always maintains it). Check for emulsion... which would be water in the oil.
Also look at the radiator fluid.. check for oil. A drop or two is no big deal.. might be left over from an old rebuild... any more than that and might be an issue.
Check the condition of the rims... rusted rims make for a good bit of work to repalce.
Check steering linkages, and see how much play their is.. clutch ( or hydro trans )... check for smooth operation in all gears / ranges.
Listen for odd sounds, etc .. check engine at all ranges.. look for stumbling / rough idle hesitation, etc ( ping / knock ).
How well does it start? smoke alot? Was it could when you looked at it and tried to start it? ( best ).. or was it warmed ( some times a tractor starts better warmed up.. so the previous owner warms it to make it start better.. so it will sell... etc.
If it has hyds'.. check them.
Do alot of research, look at alot of tractors... have fun
good luck
Soundguy