iPad/iPhone currency exchange app+web for private biz use

I'm looking for an iPad/iPhone currency exchange app for private business use. This app needs to be accessible on iphone and also ipad. The app will work like the FXCurrency calculator on appstore where a person enters an amount in one currency and will be converted to another currency. Currency conversion rates on buy and sell of each currency is set by limited set of users. There will be numerous pair of currency with fix conversion rate based on how much buy and sell. App will be in chinese (traditional). I will do the translation for all the chinese character. For example, user can input rates of: rate 1) between 1 to 10000 USD buy 1USD=77JPY / Sell 1USD=76JPY rate 2) between 10001 USD to 30000USD buy 1 USD=78 / Sell 1USD =79JPY rate 3) between 30001USD to unlimited USD buy 1 USD=80 / Sell 1USD =81JPY A regular user creates Book A enters in calculator to sell $1000 USD for JPY and will provide converted amount in JPY. Using rate 1, the result is Sell 1000 USD to buy 7600JPY. User clicks ok and the transaction is completed and prints out invoice + record number = date+number (ie:20120127-A001) Each transaction will have a record number saved to an existing local server that user operates. Pass record can be searched by user. Each transaction will print out an invoice from the iPad on a LaserJet printer with transaction details (amount buy/sell / userid/ timestamp) + record number. certain users will be able to view how much of each currency they have on certain book based on transaction. Admin can deposit or withdrawal with transaction number and time recorded For example, at Jan 27 4:00pm, admin user deposits 50000 USD and 100000 JPY in book A. Based on above transaction ID: 20120127-A001, the user sold 1000 USD which deduct the grand total of USD deposit to 49000 USD and increase JPY deposit to 107600 JPY. This Book A amount is viewable to certain users. Admin user can create a private Book B and deposit 10000 USD and 20000 JPY @ Jan 27 5:30pm. A new Transaction ID of 201020127-B001 is created and store on server. The above transaction ID: 20120127-001 amount does not add to this book. Admin user can see the grand amount between Book A and Book B (which is 59000USD / 127600JPY). All Transaction details will be printed on paper via the iPad. App needs to be able to print chinese. I will use any possible off the self printer (HP LaserJet P1102w for example) to print from airprint function or connect physically to printer (if that's possible). Transaction details are printed on A6 size paper All transactions are required to store on hosting server which i currently have. Graphically, it does not have to be pretty. I value functionailty and reliability above all else. It has to be simple to use . Please see attached for mockup. budget is around 2000-5500 HKD