How much more agile can you get anyway ?

So I've been playing a lot of Crackdown recently. I really enjoy this game even if it's a little easy. I'm done with the storyline and am now working on the (pointless but fun) achievements. I really like what they did with them in this game, except perhaps that I have 499/500 agility orbs. Yes, I'm missing one and it's driving me crazy. I was at 467 when I beat the game and got to 493 really easily. From there, I was able to get to 497 in one night and then 499 in 2 more nights. I've been stuck at 499 for like 5 days now. I swear I've visited every inch the map at least 10 times. Finding one little green orb in a huge map is not easy. And don't even get me started on the hidden orbs. I'm at 226/300 and have no intention of ever trying to get them all. This is just crazy. I do hope more developers follow the example set by this game in terms of achievements. You get a good number of them by simply completing the game but the rest are really well done and innovative. I can't wait to see what the additional 100 points they will distribute through DLC will be.