Hi hellaflush,
Welcome to IIS.
I have a 130mm equatorial scope and was finding it so difficult to manouver in the dark (without goto) that I built a new base for it and turned it into a dob. Works a treat now.
If I had $500 to spend on a scope I'd get the 8inch dob. without question. You'll see a whole lot more than with the 130mm. I've had an 8inch on loan from the local astro club and was able to carry it and move it around quite easily.
There is a website that shows exactly what you can see through various sized telescopes but I'll have to do a search, because I've forgotten its name. Someone else here might remember.....Suzy are you there???
Astrophotography is a whole other ball game so I'll leave that to the experts, but you'll definately need an equatorial mount for that.
Hope this helps, and I'll get back to you about that website, if no one else chips in with it.
Molly.