I recommend to give the transfer job to some car dealer. They have all forms in their shop and know what's requiered in copies. Especially if you buy from a farang. For my motorbike they charged me 100 thb since i bought from private and not from them. Even if you need to pay 1000,- it's worth it.
I had to pay 1600,- thb! It's up to the IO and the connected agengy. The Immigration doesn't provide Visas at all. They send you to the agency next door. At least at Cham Yeam check-point it's handeled like this.
shipping to Thailand is offered by some Shops from overseas, but you can't have an Ebay Account or Ebay shop in Thailand. In fact, there's no Ebay in Thailand. What are you smoking?