Actually it doesn't take more money to make your car "SLICKER or SHINNIER" once the clear is layed down, it's all labor from there.You can do that yourself, have the shop paint and clear then you do all the labor. If you want them to colorsand and buff it will be quite a bit more, it's alot of work, almost all of it is sanding by hand, over and over again.
Put all the clear on at once. Let it set for a day or two, then start the color sanding.Depending on the clear, you can start sanding the next day, if your in a hurry or a production shop.
There is such a thing called "FLOW COATING" and I have also done this,I will post a pic of a truck I did. Flow Coating is when you finish painting your color then your clear, just like everything else, but you sand the clear with 500-600 grit wet sanding, then re-apply another couple coats of clear. This is alot of work, but the finish is awesome. I didn't flowcoat my bird, but I did colorsand and buff it, and the finish is killer. You could clean your teeth in the finish like looking in a mirror. I'll post pics of both.