I get them from a local racing store. It's about a 45 minute drive for me, but they have good pricing on them. Oddly it's the only thing I buy there because everything else is pretty overpriced. They are a bit big in oval track racing, which is what that shop does, so there might be a shop near you that carries them. I haven't really looked much into getting them online. I feel better supporting small local businesses like myself. Technically a Uniball is probably going to be about the same price. But you will need to drill out and sleeve your spindles. They travel about the same. Uniballs are a bit bulkier though, so if I can get a Howe joint that simple fits with no work, it's worth it to me. Plus they look pretty damn cool. They are rebuildable too. The top is removable and you can replace every part. I found this place that sells them for $77, but I have not dealt with them.
http://www.stockcarproducts.com/susp7a.htm I pay about that after tax. I can't find anyone online with the K778 from Howe, but they do make them. I had to cross reference the PN to the vehicle it came from, and reference that in their Howe book and have them order them. They keep the K772 on hand though, apparently it's a common one.