While limits do exist, there are no limits on the number of Trades that can be shown, as far as we are aware.
The limits that exist are the number of Trading partners that you can have and the number of Trades that a player is allowed to post at one time.
In my own game I have seen as many as 26 pages of Trades (mostly garbage, sadly) and as few as 4 (also mostly garbage).
We might discover a limit if all of our trading partners (200) suddenly posted as many Trades as they could, but I somehow doubt that that will ever happen.