I sold a GotH q9 Tactics for 55k, and bought one the next day for 23k. Both were gold, max, insc. The one I sold was completely clean, and the one I bought had junk mods on it.
EDIT: I hope you're not doubting me, Ignia... >_> Anyway, the person seemed to really want the shield. They offered 35k, and I wasn't sure I wanted to give it up. They offered up to 50k, and I asked if 55k was a deal, so they took it. There are some people who will pay extra for a skin they really like... Guru's only a guideline. In the end, the price is determined by the two individuals trading.