The estimated budget for a solo trip across India depends on various factors, such as the duration of the trip, the mode of transportation, the type of accommodation, the activities and attractions, and the food and drinks. However, a general guideline is that India is a relatively cheap destination for travelers, especially compared to Western countries. According to some travel blogs and websites, a solo traveler can expect to spend around $20 to $40 per day on average, or $600 to $1200 for a month-long trip. Of course, this can vary depending on one's personal preferences and choices. Some ways to save money on a solo trip across India are: taking public transportation or renting a bike or scooter, staying in hostels or guesthouses, eating at local restaurants or street stalls, and avoiding expensive tourist traps or scams.