Yep... a lean to is not only cheaper, but easier to build!
Here's the one I built, 12' wide, X 10' deep (inside) for about $800 in materials,
(had 2 carts at the time, and needed winter storage for both of them!)
I leaned towards the back for a larger door opening, 7' high X 5' wide, (both lifted carts),
I wish I would have made the door opening just a bit wider, it worked well for me, but my ex had difficulties with it!
Click pics to enlarge:
Golf Cart Storage 003.jpg
Golf Cart Storage 005.jpg
Golf Cart Storage 004.jpg
Golf Cart Storage 007.jpg
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Note:
I "over built" it because of the nasty storms and "iffy" trees in the area,
and also wired it for lights and 110 outlets on all 4 walls,
so... your material expenses should be quite a bit cheaper!