I was wondering that myself. I have loaded and unloaded several 125s by myself, but that is 6' and the length helped getting it in and out of the truck.
I unloaded a 110 (basically the same thing but only 1.5' deep) alone and it was not easy or fun!
I have no idea what second hand tanks are worth over there so I can't comment on how much of a bargain it is, but IMO buying a tank of less than ideal proportions just to save a few bucks seems stupid to me. How many years will he have the tank for? Every time you'll look at it you'll think "gee if I had have saved/spent a little more or waited for another to come up". For fish like oscars the 30" height is going to be wasted, you'll be able to keep more fish in a 5x2x2' despite it being the same volume. Whats a little extra money spread over 10+ years of owning a tank?
Personally I'd never buy a tank that is taller than it is wide for central/south american cichlids.
If the tank is a perfecto/marineland the 4x2x2 does not have a tempered glass bottom - I found out the hard way myself - cracked. The only way they replace it is with original receipts for the perfecto stand. The 5x2x2 has a tempered glass bottom - a much safer bet.