I've only ever had GTX 1060's hooked up. It varies, but lately (after power) I've been making around $0.85 - $1.17/day/card. I mine a mix of Zcash, Ubiq and Ethereum. All of the cards I've purchased have cost anywhere from $170 to $260. They ROI pretty fast in my opinion, but resell value not as good as better cards, relatively speaking.
All my 3 gig cards already stopped working with Ethereum due to excessive DAG file sizes, so I moved them over to Ubiq which uses the same ethash algo and still works great.
Another Ethash coin that the 3GB 1060s can mine is MUSIC; I feel it has better prospects that UBQ, too. Mind you, the very first coin I mined was UBQ - using a single 1050Ti (!!!) - so I am somewhat familiar with it, I just think that the whole smart contract shtick will be done better by DERO (CryptoNight - currently overrun by ASICs so don't even bother trying to mine it with a GPU).