Would you believe I bought the same set you are considering for $400? The tag said $500 and I asked what the owner was willing to take. She asked if I was OK with $400. The quilt store never got around to using it for the kits they planned to make. Eight of the dies were still shrink wrapped. Even though I have a Go with loads of dies, I couldn't walk away from this deal.
Once you use a Studio cutter, the Go seems like a toy. The Studio is meant for production as it cuts 10 layers with one smooth pass. The Go is useless for strip cutting as it moves around as you are cranking. The Studio weighs 55 pounds so it doesn't move at all and I get 50 2.5" strips with a few easy cranks. The Go dies are cheaper and with an adapter, can be cut using the Studio (still only 6 layers). The Studio dies are made of wood, expensive and heavy. Accuquilt does run sales at 25% off on a regular basis and just had a 40% off sale for Studio dies.
When you contact the seller, ask her what is the lowest she will accept as you don't want to insult her with a low ball price. I would expect she will come down to $1,000 and might go as low as $800.