I prioritized your requirements by the order in which you listed them. The first one was a zoom from 6-24X40. For a 3x zoom that would be either a 6-18 or a 6.5 to 20. Target turrets seem to be important as they were listed second. I agree and I like target turrets, especially for target shooting. The next one was mildot reticle. The fourth one was side focus. And the last one was the price range, which seemed to be pretty specific so is probably more important that it seems.
At www.4scopes.com/buckmasters.htm you will find a Nikon 6-18X40 with side focus and your choice or either target dot or Nikoplex for $291. As M4-TUNA so rightly said, if you don't really need Mil-dot, other reticles work fine and you can save money (especially for target shooting.) I realise this one is only up to 18 power (3x zoom) but the price is right where you were looking, has side focus and target turrets.
If you look at www.www.4scopes.com/monarch.htm, you can get a Nikon Monarch 6.5-20X44 with an adjustable objective. it is closer to your requested range of 6-24, but it does not have side focus. It also comes with a sunshade, target turrets and your choice of reticles, including an illuminated Mildot. The price ranges from $416 to $567, depending on the reticle, again remember what M$-TUNA said.
I have this one on my .308 and it is magnificent. I do not have the Mildot, I selected the Nikoplex but would suggest the target dot for long range target shooting. $416 for the target dot or the Nikoplex.