Let me see if I understand the basic facts:
Selller was going to drive part way to meet you.
Selller had inspection and then backed out of the deal.
No idea of "personal" motivations but sounds like seller found out cost of getting it road worthy to drive part way was going to cut way into sale price.
Repack of good bearings is not expensive, but replacement of 4 might be a few bucks, What about tire age? Might have been told all four
tires were not road worthy due to age or dry rot. Bearings and
Tires would be a fairly significant chunk of money out of the already agreed on price.
Dual axel trailer without
brakes is a little iffy too, so if inspection turned up totally rusted
brakes that would be even more loss from the sale price.
AND most important seller has to shell this money out of pocket BEFORE getting paid the sale price. Might not have the funds available.
If I wanted to continue to pursue the deal I would find out the cost of
tires, bearings, and
brakes. And cost of magnetic tail
light rig. Contact the seller and ask point blank if the problem is cost of getting trailer road worthy to meet you. If it is find out what seller believes needs to be done.
Now comes the dicker and deal part. Will seller reduce price to accomadate those required repairs if you drive there to take delivery? You are going to pay for the repairs and do all the driving so price should be reduced. Since you will have already explored the cost of most likely problems (bearings,tires,brakes and lights) you will have an idea of a fair price reduction.
If seller is not willing, then they probably have a better offer. Or is trying to jerk you around on the price. Time to let it go, they keep the trailer and the bad karma.
If price reduction is agreed to then insist on one
escape clause, that seller email the list of items that seller states require repair and that inspection by repair facility confirms that list as being the only repairs required to be road worthy. And subject to inspection by purchaser that trailer is in condition acceptable to purchaser.
If seller agrees in written email then send $20 to seal the deal. If not would you buy a used car that dealer would not allow you to inspect and have car looked over by a mechanic? If seller is willing to agree to reduced price but not inspection it's clearly time to write it off.
You and seller go to shop where repairs are going to be made, they look it over if it's good then seller gets money you get
title and you pay to get it repaired.
Worst case your out a trip, $20 and maybe the cost of the inspection. But bearings, tires, suspension and brake inspection should not be even an hours labor.
OR
At one of several points along the way you find out this seller is not really on the up and up so just walk away. Knowing you are probably dodging an unpleasant experience.
Trust your instincts more than your emotions when dealing with money and stangers. Instincts that something is "not quite right" are always based on something, even if you have no idea what it is.