Karsten
I do agree with you there good things. I get my batteries from work at a staff discount which is very good value , good quality Caterpillar start or deep cycle lead acid.
My Bukh a easy starter and as far as my house batteries are concern they were free as we replaced two on a second hand grader and they were distended for scrape If I had not asked if I could have them.
So I have spent around $120 for 420 amp hours plus the original start battery 120amp .
At the moment I have a very very large list of B.O.A.T $$$$$ to send which if you ask Cisco he might explain

and I need rigging and sails and a working stove way before I even think of any other batteries .
Ive never seen my batteries under 13.2 volts. (Thats with all my LEDs switch on at night with my fridge going plus my stereo )But I have not been living on her yet and have not gone through a Mexican winter with every thing conected. So I have to wait for a while longer to work out exactly what I need and use as far as power goes and even then I still have to raise the mast and rigging plus sails and see what shading effect Ill have .
I will fit two 12 volt 120 watt flexible solar panels on the cabin roof soon which will reduce what I was getting of my LG solar panel which is 300 watt 34 volt .
Time will tell for me

and budget as well