Bart,
Price is too high. Junk value (0-60 cent per kilo) is enough. A new one will cost about 170-200 euro, so 60 for a battery of which you do not know age and history is always too much. Try several truck dealers and explain where you need those used batteries for. If they are interested, hand over a box of cake to glue the relationship. Do not pay more than junk value and ask if you can return the ones that cannot be revived.
Thirteen is right. Semi's are often undercharged. Some can be saved, some not.
Regards,
DJ