Went and ate lunch at Thai Express today. Not bad and cheap. $5.50 or $5.95 for everything on the menu. The green curry beef had a decent intensity and the beef was tender. The pad thai was definitely of the darker variety, but balanced and not really sticky in the bad sense. Both were good sized portions.
The people there are very nice and the wife who does all the cooking is from Bangkok and the husband is from Laos. They often have really cheap specials ($3 for some crispy fish in chili sauce today, I think).
Since it's just her in the kitchen, it can be a bit slow if there's a rush. But even with the 8 people ahead of us today, our food came out in less than 20 minutes. Probably the best option in that area (right across from the old eastgate theater, now a church, and near the new PCC campus). The only other one is Bai Yok truly near there. Although Arawan, probably better, is only a mile or so down the road and you could drive a couple miles to Cha Ba.