advice Should I sell or stand by my last offer?

Hi fellow domainers, I need some help.

I have received a 1000$ offer for a 7L brandable on BrandPa last Friday.

This is the second time (within 5 months) the same buyer makes an offer for this domain. The first time, BP's agent managed to agree to a 1299$ final price but, in the end, the client bought another domain instead (as told by the agent).

Shortly after that, I lowered my listing price from 2499 to 2199$.

Now, the same buyer has come back with a 1000$ max offer. I suppose he has seen the price drop and has lowered his offer accordingly.

Given the fact that there is a real interest from this buyer, should I sell the domain for 1000$ (750$ net after 25% commission)? Or should I stand by my last offer of 1299$ and see what happens? Would I be risking losing this client forever? Also, what kind of person do you think this buyer is, an end-user, or an investor?

I am asking this because this whole story of buying another domain and coming back a few months later sounds a little weird to me.

FYI: The domain was hand registered around April this year for around 7$.

Thanks a lot for your help!

Jose