My solution is a Tamron SP 90mm f/2.8 Adaptall-II (model 72B) which gives me 1:1 magnification and a comfortable working distance for just under £90.
Doesn't have the same reputation as the earlier 90mm f/2.5, so prices tend to stay low.
(Edit: some details here)
On my X-T1:
strawberry by Jean-Yves, on Flickr
greenongreen by Jean-Yves, on Flickr