If you're not picky about how your RV looks, do it yourself. If you want it to look professional, pay the $3K. I would venture to bet that I'm more handy than most and I tried repainting an area along the roof that couldn't be seen from the ground and later tried the two part clear coat everyone was using to repair an area that was just starting to have issues. After everything was said and done, it still went bad and got worse a couple of years later.
I finally paid to have my entire roofline repainted above the drip rail. Since it's typically dark colors that cause issues, I had them change the roofline to one of the coaches lighter colors (on the lower body) so that it looked like it was just another color change in the scheme.
Since this is an issue with a lot of coaches, many people buying used coaches are savvy enough to check for this problem and could hurt resale in the future.