Zcash Profits would be around $3 per day at today's rates which comes to about $90 per month, so you calculations are pretty accurate (slightly lower for Eth).
Mining profits have crashed drastically over the past couple of weeks, and it does not look like a sound investment anymore, I would not recommend getting into the mining game right now.

However I am hopefull that Ether price will recover from the rock bottom it has hit. Zcash may not, but with block rewards growing it can gain profitability nonetheless. A lot of people are buying these coins right now betting on their future. Lets see if things improve in the next couple of months.