A lot of this will turn on what you, Tigger, think of as "middle range" in price terms. If you want cheaper than the £300 for my Yamaha, Many of the old Eko 12 strings are to my ears very under-rated, and having bolt on necks (in many cases) action issues can be easy to fix. But the neck will be a lot wider than the Yamaha.

If on the other hand you think (like other posters here) of upwards of £1,000 as "middle range" then I know of a young lady who was selling and may still be selling a gorgeous Ovation Adamas 12 string, carbon fibre top and all the toys including onboard tuner - it was list price nearly £2,000 new, but is probably a lot less now (if still available).