Hi Arjoo! There are a lot of places that one can explore around Guwahati in that budget. If you are looking for nearby places try this link: https://www.tripoto.com/trip/seven-best-weekend-getaways-from-guwahati-5a1052ab9775f . Nepal and Bhutan are also options, if done with planning and using public transport. Stay with the locals, eat with villagers and explore the local life. Hope this helps.
Hey u can visit shillong from Guwahati and from shillong u can visit to Cherrapunji and Dawki, it would just 3-4 hours maximum for u to reach shillong from Guwahati and it will cost you only 300 if u take shared sumo, and even u can visit in Guwahati worlds smallest river island Umananda that is in Guwahati.