Just this. BUILD YOUR OWN
I went looking last year for a similar size for my father's garden.
What people wanted £5000 quid for was literally matchwood. That's not a typo, that's five grand!
I helped my neighbour 'assemble' his shed, it was a summer evening, bright and hot.
OSB base on 2" batons (FFS) and shiplap sides. We got the roof on and suddenly I was panicking like crazy, the walls appeared to be on fire! Turns out they were so thin that the late evening sun was shining thru them, like when you put your hand over a powerful torch!
I built this a few years ago from scrap.
I began by making the roof trusses from pallets & crates. You can stand on them!
I even made the doors.
Use recycled timber for the frame & trusses, OSB for the roof and sides. As long as you use a membrane and good quality cladding it'll last for years and be something to make you really proud. 'I
MADE this!'
As Rob says above, insulation, power/light and lining all help to make it yours. Avoid creosoted wood, it smells and burns but fierce!
Tools: Hammer, drill, saw, measure and a chop saw if you need to make a lot of repetitive cuts. Nails, glue felt, screws, nothing special
Go on! It's a Dad thing . . .