Leaning towards this Suncast 6x5.

https://www.wayfair.com/storage-organization/pdp/suncast-modernist-6-ft-w-x-5-ft-d-resin-vertical-storage-shed-xa10272.html

Also considering this smaller steel one.

https://www.wayfair.com/Aiho--Aiho-6-ft.-W-X-4-ft.-D-Galvanized-Steel-Horizontal-Storage-Shed-CC10-L510-K~AHOB1028.html?refid=GX657458825943-AHOB1028_65754512&device=c&ptid=1612806444853&network=g&targetid=pla-1612806444853&channel=GooglePLA&ireid=226476175&fdid=1817&PiID%5B%5D=65754512&gclid=Cj0KCQjw1_SkBhDwARIsANbGpFvHslFmXAvP7knx-eIW_hQ_Wkkd1IbC2x1duNCsm_4y7QY2-o47fIEaArvOEALw_wcB

Does anyone have other suggestions?

I looked at the various options and ended up building my own…

If the physical size of this will work for you, then it will keep your stuff out of the weather. How it's going to hold up will depend on the coating and how it's abused. It's fairly thin and probably 29 gauge. That's not terrible, but corrugated metal at 29 gauge can be snipped and torn by hand, so if you snag that thing with anything, it may get a hole pretty easy. For what it's worth, 24 Ga R panel to cover the outside would approach the cost they are charging for the entire shed. That's not good or bad, just manage your expectations. As Ben above noted, 29 is about half as thick as 24 ga paneling. It is also going to be 'light'....about half a pound per sq foot, so make sure she's secured.