This is a magic question everyone asks each time they buy/sold a sword
For me these swords are no-no, because:
- polish is bad
- condition unknown, will revel after polish
- Koshirae needs renovation, seems not to match (guess based just on photos) same theme for Fuchi/Kashira
- For 500-1000$ you could buy something in better out-of-the-box condition from Japan
This is just my private opinion as I have a very specific key for swords in my collection. I always like to have "pristine" (or close to it) look of the sword. This means perfect condition, polish, Koshirae. Even for a 300-500 years old swords.
However, I know there are collectors that value 'original' condition more. With old polish and Koshirae, even if it is falling apart.
Still, IMHO if you buy them for 500$ then you should be able to resell them for same (maybe more?) price. So maybe worth risking.