Need a new battery for my 200 tdi 110. I need to power DVd's, phones, fridge so was thinking of fitting two reasonable batteries (nothing too special) Is it possible to get a decent battery for £50? Also, how do you fit two batteries?

I'm looking for a series III, fully retored/prepared and live near Shrewsbury in Shropshire. Whar are the best web sites with lots of such vehicles for sale? where are the best dealers for such vehicles? your help/advice is appreciated.