(edited by a t s e.9614)
Reserving item with taxes?
if you have an item, you can do three things: match lowest seller, match highest buyer, and create your own price. The first one posts an item at the lowest price any other sellers currently have their up for. The TP will hold the item until you remove it or it sells. The second sell it instantly to the highest bidder, which is usually lower than the sell price, and the last is self explanatory.
If you want an item, there are two things you can do: buy from lowest seller, or place a buy order. The first one instantly gets you the item, but costs more. If you place a buy order, you spend the money now, and the TP holds it until you either remove the order, or it gets filled, and then you get your item.
There is no way to set a range you are willing to spend and let the TP do the buy if an item becomes available in your range for whatever price it was posted for.
RIP City of Heroes