Rather than buy the expensive switch, Can you run a Crossover Cable between two machines?
Basically
Server with 2 network cards
Card 1 = 1Gbps connected to router with internet
Card 2 = 2.5Gbps connected via crossover cable to Workstation Card 2
Workstation with 2 network cards
Card 1 = 1Gbps connected to router with internet
Card 2 = 2.5Gbps connected via crossover cable to Server Card 2