Thanks all, for the help.. Glad I asked.
I sort of ran out of money for this project until some of my customers settle their debts, so I'm part of the way there..
Got the batteries from Sams, hopefully they'll hold up.
I put two Duracell AGM Golf Cart (200 ah) batteries in series on the house side. (I have just enough room for two more in the coming weeks, for a series/parallel wiring)
and two Duracell 12v 55ah Marine AGM's in parallel on the alternator for starting.. Why two? Well, I'm a little nervous about a failure in the series and somehow being down to a useless 6v leg, so I see the second 12v AGM as a hot-standby that could be readily re-wired or switched, at least until I can complete the houe bank in the coming weeks..
As it stands, it gives me 200 ah rated bank on the house for now and room to add two more identicals and push up to 400 in the coming weeks when I'm feeling froggy...
Thanks again for the suggestions, Sams prices were really pretty reasonable, especially compared to West Marine and the Auto parts dealers. Hopefully the reasonable price doesn't bite me.