Loaded question on mower - battery or gas

Hey everyone! my wife and I moved into our first house last year towards the end of the season and just paid the local landscaper who was cutting a lot of our neighbors yards. I am not looking to keep up that expense! We are on 1/3 acre which the majority is somewhat of a slant/hill (not horrible, but decidedly not flat). I am accustom to an unpropelled gas push mower from when I cut for my parents on their 3/5 acre. The problem I have is we currently have no outdoor storage. I am trying to be monetary conscious and I don't want to buy a decent gas mower and have it rust out before I can build a shed (probably wont be able to make that happen til the fall). This is what led me to research the rechargeable battery mowers. Most are a thick plastic decking which will prevent my rust concern -it also could be brought into my basement since there wont be gas fumes (tho I guess it would smell very grassy down there). With a 1/3 of an acre I know I would need 2 batteries, but I am not positive if that will cut it. Looking at the ryobi 40v and the black and decker battery models. Would like to keep my purchase below $400.



Anyones thoughts would be appreciated

1) buy battery mower and have 2 batteries

2) buy cheap gas powered and throw a tarp over it (don't plan on it lasting more than 1, 2? seasons)