M&J Guest House/Ayutthaya is cheap, I really didn't believe 100baht per night places existed anymore in Thailand.
This guest house is on Thanon Pa Maphrao(Coconut Road) just pass the Por Gun.T Bar, you have to go down a tiny dirt road to get to it, the road is a dead end so to get back onto the main road you have to reverse out whilst trying to avoid lumps of concrete etc etc etc.
Good Points;
It was clean.
Bad Points;
It is made from wood so is poxy noisy with people getting up at first light.
Only one plug, so you had the choice of the fan being on or charging your batteries.
If you come back at 4AM you will find the compound is locked which then entails drunkenly trying to clamber over the poxy wall.
Shared Bathrooms.(but they were clean)