They start with a promise of a high salary, then when you have done the test AKA wite a bit of the code for free,. If they do this after a while they will have the full code for free.
Afterwards they got your code they come with the low ball offer. Just think of working at Ryan air and Michael O'Leary you won't go far wrong.
Judging by the offer, this lot are still in the slave trade.