As herring had mentioned to get the interbank spreads you need to go up to $80-100k account size. Although the minimum is $25K at aarontrade.com the minimums for the expanded Currenex are 250K, 500K ,and 1 Million, 5 million +.
At that point, depending your account size and liquidity needs you can have additional liquidity on top of what you see on the 25K account size. As it mentioned on their website there are other possible requirements for the expanded versions such as 1, 3-5, and 5+ yards a month.
The largest of the expanded version appears to be if you trade more than 100 million, 500 million, and 1 yard+ at a clip.
However, even on the $25K account Currenex the pip spreads are 1 pip sometimes choice. Starting at $30/Mio with NO pip markup. Maybe the pip spreads are tighter more often on the expanded Currenex. For example, maybe for 5 Mio its choice nearly all of the time. Not sure on that one or the minimums for Currenex API connectivity, But the minimums are $25K if you go via APIth through eir fully intergraded platform. Which will achieve the same thing as communicating through the Currenex API.
Although you appear to need 5 million + for direct access into their system. Which judging by what I read they will accommodate but it appears to be for funds only for direct access into the system. This appears to be accessing a whole world of other liquidity outside of just Currenex even on the larger expanded version.
So all in all you certainly arenât going to get all the bells and whistles for 25K but surely better off with Currenex or Hotspot etc. than going MM. If you only trading in the range of 25-50 K all that liquidity shouldn't really be needed anyway.