Hi Rob...welcome to IIS
Dave pretty much hit the nail on the head with what he wrote, however, if you want to do long exposure astrophotography with an LX 90 ACF, you can. You can get a wedge for the mount, just the same as you can get one for an LX200, but the LX200 drive system is more robust and has a few extra features. In any case, you can get yourself a camera like a GStar EX, Mallincam, DBK21-41, Watec or Stellarcam (low light video cameras) and use the LX90/LX200 in Alt-Az, as they take multiple short exposures in quick succession, which you can stack later on to produce an image.
The ACF models have considerably better off axis performance than the normal SCT...I know from experience, as I have an ACF myself. They are wonderful visual instruments and are very good for piccies as well
Your budget of $3000 has sort of limited you to the smaller apertures, even an older model LX200 in 10-12" would be worth more than $3000. You could try the IIS Classifieds, but I think you'll find they're still worth more than that.
If you want to get into piccies, for a start, you'd be better off getting a shorter f ratio apo refractor on an eq mount....an ED80 on a EQ6 mount would be good to start off with. They're easier to handle than a SCT plus they have a wider FoV (field of view) and shorter f ratios (f6-8 versus f10). It's also more portable. An Orion Eon ED80 + EQ6 mount will set you back about $2900...then you have to think about eyepieces, camera mounts and adapters, spacers etc etc etc. Astrophotography can be a rather expensive hobby, but one you can slip into over time as you buy extras for your scope. You also have to think about guiding your scope, so you'll need an autoguider (basically a CCD camera optimised for as such) and another, smaller guiding scope, or you could buy an off axis guider or a self guiding camera (which can get expensive). You can see where I'm going here. It's not cheap and you have a myriad of options to choose from, which can confuse newbies completely.
The best thing for you to do is to learn to crawl before you can walk. Get yourself a good scope for visual use first up, then move onto piccies at a later stage, once you've gotten to know the sky and have a bit of experience up your sleeve. That way, you'll be ready to move onto the more complicated areas of astronomy, such as astrophotography.