For visiting there, u first need a visa, thailand offers Visa on Arrival, so the only requirwment is a proper return ticket, proof of your hotel booking while u stay there, and a proof of you having some money(mostly they do not ask for that).... average cost comes around 60-70 k with average accomodations and travel choices for 5 days...
If you're interested in travel in Thailand you might want to try Tour bus It is the best way if not in a rush and want to enjoy the nature, Because it very easy and convenience. When I want to travel in Thailand I use Tour bus all the time. And I always make a booking online . You can save your spot by checking their website for available buses. https://busx.com/en-us