I'd start by checking with some dealers to see what is available. If you find something you like see if you can find it on ebay or Amazon for less. If the dealers don't have much try places like Best Buy (they are still in business, ritght?) for an automotive type head end. Boating shops may have these things as well.
The unit we have is OK for as much as we use it, so if it dies (out of warranty) I might look for something from the same manufacturer. Their web site would probably tell you who the dealers are.
2013 F-350 CC SB 2WD 6.7PS
2013 Eagle Premier 351 RLTS
-SOLD- 2012 X23B
-SOLD- 2003 Ford Expedition 5.4, Bilstein shocks