Ray,

Not that much. First of all, there are not many music stores anymore. Target,Walmart and Best Buy are about it as far as retail goes and their space is very limited on product. Second of all, they were always intended to be promotional for the album, star and product. So they were never really intended to be for sale.

Some, that did a lot of videos might offer them as a collection, but more than not they were as part of the CD set. Garth Brooks included all his videos and records in one giant package. He is the best about selling the same product over and over again, but in different packaging. It's how you sell 100 MILLION records in a decade.
Shania and some of the hotties would sell it as collections, but most often through their own web sites and social media.

But the biggest impediment to sales of them is YOU TUBE. Everything is availible through that for free, so like everything, why pay for it if you get it for free.

From the beginning of the music television age, with MTV, videos were always a giveaway, we are not even paid for plays on a video. It is always considered promotion. They can be very expensive and now you have to consider video as part of any promotion of any song you have. So you writers need to be doing some story boarding as well as getting the recording done. It is all involved now.

MAB