There's no cheaper way to visit around city of Ayutthaya (island) than go biking. I'd suggest a 1 day trip iternary for whom stay in Bangkok and nearby. This course is perfect for travellers who riding on a train ,the cheapest & most scenic way. (other type also applicable but start point need to be changed and direct will need a bit modified, will show you later) Departure from Bangkok's Hua Lamphong Train Station and stop in Ayutthaya will taking about 2-2.50 hrs depend on the type of service ( minibus (van) around 1 hrs/ Bus 1.50 hrs in difference place of departure).