Wanting to keep your products in a new condition isn't OCD unless you mentally cannot cope, or struggle greatly with other areas of your life if your product is damaged in some way. Calling things 'OCD' is a gross exaggeration, OCD is a genuine psychological condition that can be treated, but worrying over scratches is not even close to this.
Anyway, usually people are concerned when they perceive a high value to the product. If you're spending 100% of your salary on it, then loosing/damaging it is going to hurt you financially - as you cannot simply replace it. The easiest solution, is to spend less, if it only cost you $40 then I'm sure you wouldn't have any issue if you dropped it. So just bear this in mind, it's normal to want to keep it in good condition - it's abnormal to obsess over this. You can buy a case and just take care of it, it will pick up scratches but personally I see these as battle scars - it's the personality of the device and the time you've had it. Nothing lasts forever, give it 5 years and it'll be ripped apart for the raw materials. So it's not worth obsessing over too much. If you plan on keeping it, just take care of it and enjoy it, get a new one in a few years and be happy. If it's something you plan to sell, then put a case on it and hope for the best.
Personally, I don't use any cases or skins and stuff as I hate them. If you pick up your phone, spin it around, play with it, you'll be less likely to drop it as you'll become accustomed to it. If you put it in a case, I believe there's a perceived protective value so actually you'll be more likely to drop it. It's like when you get a new-ish car, you'll cry if it's scratched right? But ever had a 10 year old scratched up car? Don't care about it, it's a car - gets you from A / B and you're happy. Try get to that point.