Whatever you get, don't go too small.
There is a John Deere dealership about a mile west of I-5 at the Donald exit south of Portland. Never dealt with them but know farmers in the area that say they are fair and honest. Be about an hour's drive for you by way of I-205. Don't know if they are still there, or under the same management, but there used to be a couple of good equipment dealers in Battleground just north and east of Vancouver.
There are those that will disagree but all good tractors are not painted green. We've used a lot of JD stuff over the years but other brands have merit as well.
Even with 50 acres in that lush growth area your in it's going to take a lot of mowing to keep things groomed up. If you're planning on putting up any hay or doing other farming I'd suggest talking to guys making a living at it in that area prior to buying equipment.
What we do, about an hour or so up river from you, is a totally different type of farming. Lot of smaller places are too small to farm and too big to mow. They end up as a weed patch and hard to deal with. You might want to consider share cropping or leasing any hay land out and just getting a tractor and equipment for the nicely groomed areas.
Don't know how familiar you are with the area but just up the river at Stevenson is the Skamania Lodge. Great place for nice suppers. We were down there for a couple of days this week.