Gsync monitors typically command a 100-150 dollar price premium (over similar freesync monitors).
Here's the cheapest Gsync monitor I found (400):
https://m.newegg.com/Product/index?itemnumber=N82E16824160226&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-PCPartPicker, LLC-_-na-_-na-_-na&AID=10446076&PID=3938566
Basically, what freesync and Gsync does is the same; they change your monitor's refresh rate on the fly to remove tearing. Gsync monitors are more expensive even if the tech does the same thing because Nvidia has it's own special hardware that monitor manufacturers have to buy off of them to fit the standard.
Note: You won't be able to use the freesync technology on your 970 because Nvidia. That doesn't prevent you from using a freesync monitor though, it just means you won't take advantage of the tech.