Overstay 6 months

I personally know a person who overstayed for 3 years and he was not allowed by Airport authorities to leave the country.. Hopefully you will find a way..

Immigration/ government have recently increased the punishment for overstaying
On the old rules and was sometime between October 2016-January 2017 ? they was several British expats who overstayed by 3/ 6months one was deported and banned from Indonesia for quite some time one was jailed for several months and again banned from returning
For about 1 year
But to answer your question you will be arrested probably jailed and lose ticket unless you can prove you've been in a coma for the last 6 months

A million Rupiah per day is the new rate, but I'm unsure if that's backdated for days before the new fine was introduced.
If you have no cash for a ticket, you need immediate funds from family/friends or, and this is only a vague hope, assistance from your embassy.

However, I gather immigration is getting pretty keen on overstays so you need to do something quickly, that including the cost of flight tickets and assume a fine of 180 million (The fine for 6 months up to today), perhaps a little more of less depending on how accurate your stated 6 months is.

Personally, I have no sympathy for foreigners who radically abuse the immigration laws of Indonesia.  Those laws are not so difficult or expensive to comply with, and it is an affront to those expats, who for years on end have complied with the laws.

Pasal 78 UU 6/2011
1) Orang Asing pemegang Izin Tinggal yang telah berakhir masa berlakunya dan masih berada dalam Wilayah Indonesia kurang dari 60 (enam puluh) hari dari batas waktu Izin Tinggal dikenai biaya beban sesuai dengan ketentuan peraturan perundangundangan.
2) Orang Asing yang tidak membayar biaya beban sebagaimana dimaksud pada ayat (1) dikenai Tindakan Administratif Keimigrasian berupa Deportasi dan Penangkalan.
3) Orang Asing pemegang Izin Tinggal yang telah berakhir masa berlakunya dan masih berada dalam Wilayah Indonesia lebih dari 60 (enam puluh) hari dari batas waktu Izin Tinggal dikenai Tindakan Administratif Keimigrasian berupa Deportasi dan Penangkalan.

1) Foreigners holding an expired stay permit and still within Indonesia fewer than 60 days past the expiration of the stay permit will be fined according to the law.
2) Foreigners who do not pay the fine stipulated in (1), will be subjected to Administrative Immigration Action, in the form of Deportation and Blacklisting.
3) Foreigners holding an expired stay permit and still within Indonesia more than 60 days past the expiration of the stay permit will be subjected to Administrative Immigration Action in the form of Deportation and Blacklisting.

You better go to your embassy in Jakarta.Ask them to help you.

Hope find the solution
R.Siregar