Depends on a lot of things...is it on the face of the guitar (obvious to others, or only to you). How hard would it be to match the color ( There's automotive patch paint, fingernail polish, etc...), Do you want to have the coolness factor of SRV's number 1 on your PRS, worn, torn, but looking totally well abused, ... -OR- do it right , yet more $$$, and send off to PTC...
BTW...I've been able to get really close with "Sharpies" when it comes to patching some of my mishaps...luckily, most have been on black backs, and Black sharpie does just fine. Also, Clear nail polish on natural , etc...