Always been a fan of White Elephant and Delicious Thai for cheaper and great Thai... Chili club Thai is not bad either but it's a bit more expensive than the first two.
White Elephant is funny since it's located in the corner inside an older hotel, you always have to walk past a bunch of Indian cleaning staff hanging out in the lounge to get to the restaurant when they were still open for lunch. Don't count much on the decor or service though... place is pretty much a hole in the wall, family run and is super understaffed
Massamun Beef with 3 chilis, Tom Yum soup and steamed rice for $11 from White Elephant
EDIT: Sorry for big picture, posted from my phone and can't resize atm.