When I first started looking , I had much that same questions .
My answer was very simple : None compare to Japanese .
I bought a 1984 Suzuki FA50 with close to 5,000 miles on the clock , about 10 years ago . Gave it the once over . Replaced a couple things like tires , a coil and fenders . Adapted a tail light I had and been riding worry free since . That , until the mud daubers totally filled the exhaust outlet and had me stumped for an hour or so .
Oh , I had a major expense recently : I had to buy a new inner tube because I could not get the old one to hold air for long . That cost me a whole 10 bucks , but , I did buy the heavy duty version .(edited)