The reps are a teeny bit too flexible, so be careful when handling them so they don't get any kinks. Those can be worked out with a heat gun, though. Otherwise, the quality is great.
I did paint them myself. I went to NAPA and got some spray cans of color matched paint ($35 each) and bought some SprayMax 2k Gloss Clear coat online. I also had primer for plastic (can't remember which one) and sandpaper. Sand, prime, paint, paint, paint, sand, clear coat, clear coat. Easy enough in the right conditions. If you take it to a body shop, estimate about $150 for paint which, honestly, isn't much more than you'll spend on supplies.
The reps do come with something to secure them. So first, you're obviously aware of the 47 screws underneath the stock side skirt. You'll remove all of those and reuse two. The reps come with these plastic squares with a hole in the middle and another small piece of square plastic that goes in that hole. What you do it find the two spots on each rep that align with the rubber oval underneath the car. Pull those ovals out (be careful of all of the dirt that's going to go flying). You then take the big squares and wedge them in those holes. Then you take the small squares and wedge it into the hole in in the big pieces so that the big piece expands in the opening and secures itself. You'll then need to buy some screws of the correct length and some washers to secure the side skirt to the screw holes in the big plastic piece. I think I used #10-24 9/16" and the washers were AA.... they're pretty wide, maybe 1/2". You'll also need to use a screw in the front wheel well (there's already a hole on the reps for this). I'm making this sound way more complicated than it is; you'll see what I mean if you buy the parts. If you buy them and still don't get it, I'll get under the car and take pics. You'll then need 3M double-sided tape or a glue to secure it to the car. I used 3M double-sided tape (#38583) and it's held up great in the heat and rain... we'll see how winter goes.
The only problem is that the reps are 1/4" too long in the rear, so I ended up buying screws, washers, nylon spacers, and expansion nuts. I drilled a hole into the rubbery part of the rear wheel well and put the expansion nut in there. I put a spacer in the gap and then used the screw and washer to secure everything. The only reason I did this was because I was adding weight onto them with the Dutch Parts Co stuff. If you're not doing that, I don't see a reason to secure it there and you could probably just seal it up if it bothers you.