This is a complex issue.   If you say you want to buy exactly $100 of BTS then the PRICE is contingent upon the order book which is constantly changing.   

We assume you want to get as much BTS as possible for your $100, if that is the case then place a buy order with a price near infinity and you will get $100 worth at the best possible price.

When I trade on exchanges, I'm thinking like this: "I'll buy 10000 BTS with the best price" or "I'll sell 10000 BTS with the best price". You see that I want the BTS amount fixed and price/USD changing. I can only do "selling 10000 BTS with the best price" on BTS2 but not "buying 10000 BTS with the best price" because I'm not assured how much BTS I will get. It's not a big issue because I will get more BTS than I asked but from a trader point of view I really hope BTS2 acts the same like a normal exchange.
btw, I also hope we can add maker/taker fee to improve the liquidity. Maker%+Taker% should be >= 0. The initial fee can start from something like [-0.1%, 0.1%] or [-0.1%, 0.2%] and can be adjusted by committees.

I think the fee for placing/cancel of an order and transaction should be very cheap. But the fee for trade success should be more, such as 0.0005 of the    liquild.
People are willing to pay when trade success, because both seller and buyer feel earn something at the moment they trade.

I think that the current market fee should be split into maker fee and taker fee. So we have order placing fee, cancel fee, maker fee and taker fee where [maker fee percentage]+[taker fee percentage] >= 0. The order placing/cancel fee should be as low as possible just to avoid spamming. To improve the liquidity, we can set the maker fee to -0.2% and taker fee to 0.2%, or maybe -0.1% and 0.2% to get some profit from trades like normal exchanges.

you can walk the orderbook but will need to derive the effective price on your own

Yes. But when I place the order, I only care about how much BTS I want to buy and what the worse price I can afford. It's counter intuitive to say "I want to buy as much BTS with 5 USD with price better than 0.005".

Well, I know you can sell USD and receive BTS to achieve buying BTS using USD.
I can do things like "to buy as many BTS using 60 USD" but what I can't do is "to buy exactly 10000 BTS for worst price of 0.006" if I "sell_asset xxx 60 USD 10000 BTS" when best price is 0.005.
For most (or almost all) other exchanges, you're specifying the exact quantity of BTS and the worst price you can accept.

I noticed that there's only sell_asset on wallet_api. This is fine because I can sell USD for BTS if I want to buy BTS.
But the issue is when I want to buy BTS at best price, I can't accurately specify amount of BTS I want.
Say I want to buy 1000 BTS and the lowest ask price is [100,0.005]. I want to buy 1000 BTS with highest price 0.006. What I can do is to call
sell_asset xxx 6 USD 1000 BTS .....
Now it will buy 1000+ BTS with 6 USD. But my purpose is to buy 1000 BTS using USD <= 6. It's counter-intuitive and quite different with most exchanges.

Is my understanding wrong? If not, I strongly recommend to allow a way to specify what amount I want to be fixed (BTS or USD) or add a buy_asset API.

囧 bts2手续费不是0.1bts了么

bts1最低手续费为0.1bts, bts2转账每笔最低手续费20bts. 另外它是基于operation的，所以就算在一个交易里转出到多个不同的账户也要每笔收取20bts.

I didn't find cancel_order in wallet_api whereas I found signed_transaction cancel_order(object_id_type order_id, bool broadcast = false) in https://github.com/cryptonomex/graphene/blob/master/libraries/wallet/wallet.cpp.

Is it intentional or will be added later? I noticed web wallet has this ability using js libraries.

刚发现上周有两笔分红交易EXPIRED，从钱包查不到地址，如有没有收到分红的，请在此帖提供您的bts用户名及对应的botfund数量以便重发。