Inov 222

The 222 is hard to find these days.  You might find one on e-bay if you set up a search and have patience (I've seen one in the past year or so - I think it went for around US$400).  I've never seen a 223, its successor.  Although you might have luck finding the latter used in specialty stores (but you'll pay a lot more).

The Inovonics 222 is a nice addition to an AM station.  I achieved my best AM coverage with a Hamilton Rangemaster (ground mounted) and an Inovonics 222.  That was prior to my learning that I couldn't use the Rangemaster in Canada as it is only Part 15 certified, but not RSS210 or BETS (either or are required here in Canada).