DJ Promo 45's - Interest?

Over the years I have collected a bunch of 45's as I found them and bought a few at a time whenever I found them absolutely mint. I now have a total of about two hundred. The vast majority are rock and soul DJ promos with the same song - stereo on one side, mono on the flip. For the most part, the only drawback is the frequency with which one must change the record. Sonically, most all of these sound incredible. It is fun to compare the stereo and mono sides. Odd the ones that sound better one way or the other.

Does anyone else go to the trouble of spinning these kind of 45's and do you find similar enjoyment? Also, where can one find the value of these records? Not so much that I have an idea to sell, just that I never see prices listed anywhere except for "stock" versions - juke box versions, if you will, with two songs per 45.
I think Sacd01 advertises them here at A'gon for about $10 each. I know nothing about them.
I wouldn't hang my hat on values as listed by SACD01, EM, but sincere thanks, all the same. :-)

More importatnly, does anyone else spin these?
Guess not! :-)
Well, I have a collection of 1000+ 45's (or 7"s as I call them!), but not many of the stereo/mono variety you mention. Most of mine were issued anywhere from the late 1970s up to last week.

But from what I've seen (in shops and online catalogs), a lot of the older ones--especially white-label or DJ promos--can go for crazy amounts of money. I don't know of any price guide specific to promo 45's. Might Goldmine or Record Collector (neither of which I read) contain such info?

Have you compared the 45 cuts to the album cuts? I heard that the EQ on the singles for airplay was adjusted to sound different in deference to the type of radios people used to have and their sound characteristics. Maybe boost in certain ranges?