melchior.
There are thousands of great images taken through reflectors. But the painful truth is for $500 and the telescopes you pointed to, you just won't do it. Not and remain sane and satisfied with your images, that is. For a combination telescope and mount at that price, the mount would just not be anywhere near stable enough and the scope quality "could" leave a lot to be desired. You may be able to pick up a motorized EQ4 or 5 if your lucky that has good tracking ability, (you wouldn't know until you tried it), but it certainly wouldn't be enough to mount a reflector more than 4 or 5 inches in diameter and still remain stable for imaging. You might be able to piggyback your camera with it and use the scope to guide with.
Some of the scopes shown in the linked pages ( the ones with the larger more stable mounts) would be fine to view through, but even the 200 EQ5 and the 250 EQ6 are overloaded for imaging through IMO (mainly from lever arm movement rather than weight. ie the tube is too long for my tastes on that mount). If you were to put the 200 on the EQ6 you would stand a better chance.
My strongest suggestion is to get to a starparty or imaging session with experienced people and see what is available and needed to carry out your imaging wants/needs. Goodness knows once you start down the imaging pathway you can forget holidays in Fiji with your holiday bonus. It will go to that extra item that you just have to have to catch that just elusive image.