If you buy or fix one with a salvage title the insurance company may not give you full coverage on it. The stuff I have rebuilt was not worth putting full coverage on so it wasn’t an issue.
Copart allows you to set up a free account and bid up to $1000 but if you want to bid more than that you have to set up a bond on the account.
Note that the price rises over the bid due to fees like sales taxes, storage, internet fees etc.
We were talking about liability only.