I built this from salvaged cabinet lumber and bits and pieces of retired sound reinforcement speakers. My total cost was well under $300. The speaker is a Celestion F12-X200. The only other parts I had to buy were the port and the rear jack plate. I built the cabinet from plans on Celestion's web site. It was an easy build.
It sounds loud, full and bright. I'm going to have to tweak my EQ settings, because I have been running my Kemper into a 2X12 (also homemade) loaded with 1 Celestion Silver Bell and 1 Celestion Blue (actually Ted Weber clones of these speakers). The cab sounded fine but was a little lacking on high end so I ended up pushing mids and highs to make up the difference. I definitely need to pull them back.
Anyhow, just wanted to share.