I have the one you are talking about myself. I won a Meet & Greet with Roger Federer during the ABN/AMRO World Tennis Tournament earlier this year and included was this shirt and two red wristbands. The shirt was size small though
I did get it signed
And cause my mother won a M&G too, we now both have a signed shirt
I know some sites still sell the lemon variety. You might want to try the Nike Store in Rotterdam for the blue one, though.