Only certain vehicles like the AV-21 or BARC can be repaired once disabled with the kits you are referring to. There might be another vehicle that can be repaired, but I only remember the AV-21 and BARC at the moment.
If you have one of the above vehicles, then go search the Bazaar or Vendors galaxy wide to see if anyone has one for sale. I have a few, but I'm on the Corbantis server.
i dont know which trader makes the vehicle repair kits, but they are very expensive. probably only made on demand, so unlikely to find any on a vendor. instead, you need to seek out a master trader, probably engineering.
The engineer trader can make them. They are kinda tough to make just because the materials are all obtained from space mining. On Bloodfin I've seen them selling for around 250k.