Sale Of Electronic Goods By Taking Advance Booking / Toekin Pament

I have an electronic store based in Mumbai dealing in multiple electronics and households appliances. Now I just wanted to sell out these products by taking some advance payments in terms of product booking or token amounts and deliver the product after completing the full payment by paying the balance amount within specified timeframe say within 1year. And if anybody fails to pay balance amount then his/her bookings amount will lapse. Kindly suggest me whether it is an illegal activity in sorts of Indian law context.