Very nice account combat wise stat wise, selling an account on osbot requires for yourself to have 100 post count.
Regarding price it extremely varies per who is selling, rep etc. One could sell such an account for 400$ and another might struggle to pull 100$ out of it.
Generally big pointers to "max" accounts are buyable 99s such as farming and ones that consume months to complete such as agility/rc
maxed combat accounts go for 300m from reputable sellers, so you can throw bits and pieces for extras you got and you end up on just around 450-500m
Again mind earlier comment that it all ends up on your reputation when it comes to prices.
No idea where those 400$ coming from, maybe they will buy it off ya