The sale price of a domain generally depends on the buyer's "need / requirement", "urgency" and "budget" against your negotiation skills.
If the seller comes across as too eager to sell, the buyer gets the upper hand in negotiations.
Your name is good. Logically, if EuropeBullion.com's business on this domain is still active, they should not hesitate to even buy it for a much better price than $5200. But suppose, now they don't want it somehow (their marketing guy may be changed/dead, existing one may not have enough foresight etc), it would then depend if you are willing to sell it to some other buyer at a lower price.
You read all the while how Mike Mann sold this name for $100k, that one for $150k etc.
No insult to him but he is NO magician. Things that help him: he has thousands of names, he has industry contacts, he has his publicity as a famous domainer, he can afford to "squat" on his domains for as long as he likes (3-4 years is his average) and he quotes 5/6 figures even for his worthless names. Some people bite the bullet at times and those sales become news.
So, if you analyze carefully, a domain sale price has nothing to do with brilliance of the owner, it all comes around to buyer's "need / requirement", "urgency" and "budget" against your negotiation skills and a little luck by your side.
IMHO