I was surprised on reading this thread that daatun is being talked about as if it is a dead pratice. Bros, I lived all my life in Chandigarh/Mohali, a very modern city and daatun was easily available in many places, especially on sector 22 traffic lights across the Mango Shakes Shop. The seller used to sit on the open space on pavement in the evening. It might still be available, I am not sure.
In fact Daatun is still common in Punjab villages. The most common is Kikkar daatun. The youngsters don't do it, but most of the elders do it.
At my home back in India, we had a Neem tree growing in our garden and people from neighbourhood took leaves as well as branches for medicinal purposes all the time. The tree had to be cut recently.
Nobody actually sold daatun except in Chandigarh. Its always free, just break a branch and chew away!
You can plant a neem tree in your back garden. But be careful that in summers you shall have to take care of nimolees, the small round yellow fruits which fall from the tree all the time.In themselves the Neemolis are very medicinal too! They can be boiled and the water can be used to apply to skin for various diseases. Nimolees are also used to prepare Neem Oil, which is easily available in Khaadi Ashram Shops in India for very cheap rates. You can also get Neem Oil from Baba Ramdev Clinics, again at cheap rates. In fact many popular Ayurvedic medicines are available from Baba Ramdev clinics for VERY cheap rates. The shops are located all over including Chandigarh and Mohali.
The dried neem tree leaves are also available as powder from the above mentioned shops in India.
PS- If you plan to plant a tree for daatun in your back garden DO NOT plant a kikkar. Plant a Neem. Neem is very medicinal and has multiple uses. Kikkar is just a poor cousin which grows mostly in ujaardh(desolate) places :-) Plus kikkar is thorny.