Try making your own ricotta cheese at home! It's quick, easy, cheap and so much fresher than most ricottas you buy in the store.
Put your milk and a good pinch of salt in a pot. Heat up over the stove on high heat (keep an eye on the milk as it can boil over and make a huge mess).
Just as the milk comes to a boil, turn the heat off, then add your lemon juice/vinegar. Give the milk a gentle stir, you should start to see the curds separate from the water content. Set the pot aside then leave it for about 15 minutes.
Put a sieve over a large bowl, then put a layer of cheesecloth over that sieve. Strain the cheese curds, then leave the ricotta to dry out on the cheesecloth. I recommend anywhere between 30-60 minutes. The longer you leave the cheese, the dryer the consistency will be.
From there, put your ricotta cheese in a container, then store it in your fridge.