Single driver speakers. Are they worth considering ?

I built these Aveburys by Woden Design, using Mark Audio 12p drivers.
https://www.wodendesign.com/avebury.html
In the UK you can get great advice directly from the designer and from KJF Audio who can supply all the hardware. About £250 for the drivers and other bits and pieces, £80 for the plans, and £150 for quality ply. And the cost of your own time over a couple of weekends. For that money and time it is easy to find out just how great a back loaded full range horn can sound.  If you have the space of course - one of the routes out of the compromises is a very big cabinet. These are 6’ high. 

As mentioned before, it is so easy and cheap to find out, why not try it. Pencil, or Frugalhorn, or Woden - these designs give a pretty flat response from around 40 to 14,000Hz, are really easy to drive, easy to adjust to your room and tastes - and if you don’t like them there is a market for them if your DIY skills are halfway decent. The money you save can be spent on music, or fancy cables, or whatever.