Convert currencies with the exchange rate of a past date

Is there a free/cheap service, accessible through a web service or simple HTTP/XML queries, that can convert from a currency to another, but with the exchange rate of a specific date in the past? Say I need to know how much 10 USD was in EUR on date March, 13, 2009. So far I开发者_StackOverflow社区've only found oanda.com offering this service to developers, but they cost 200$/mo, and my budget is lower.

ECB is cool! But it works if I need to convert from EUR to something. If I need to convert from GBP to something elase I'll have to find another time series :( Isn't there a service or time series provider to convert from any currency to any other currency, for a certain date? Like OANDA actually, just cheaper :)

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replying to myself, I found this: http://www.ecb.int/stats/exchange/eurofxref/html/index.en.html

You can download a single CSV file with all daily exchange rates from euro to anything...since 1999! Very cool.

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I wanted to try out Google AppEngine anyway, so I made an app for this, using the ECB rates from 1999 onwards:

http://currencies.apps.grandtrunk.net/getrate/2009-11-15/usd/zar

gives you the value of 1 USD in ZAR on 2009-11-15. See this page for the full docs.

EDIT

I just threw in the Fed's rates, going back to 1971...

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I'm not sure but try with Yahoo Finance web service for developers

http://developer.yahoo.com/

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The USA government gives away some of this kind of data.

http://www.federalreserve.gov/RELEASES/H10/Hist/

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www.xe.com go to historical rates