Can I extend my 30-day tourist stamp in Thailand at the immigration office in Chiang Rai?

Yes. Just did it. Have a photo and fill the application out before getting in line. At station one they check your answers, they use a glue stick to glue the back if your photo. They give you a plastic number. You move to station 2 and wait until your number is displayed they pull in 5 at a time In Bangkok. You go to the window. Pay the 1900 baht. Go sit outside the office and they bring passports out and call your number. They break for lunch. Shut down and everyone leaves which I found kinda funny. This is in Bangkok. Good luck. They extend one month and a day from your entry stamp. Get there before they open.

Yes you can take two photos plus 1900 thb.

It was 3 years ago I thought it was 2000 ,so I was out by 3 dollars

Yes 1900 baht

You can get an extension (assuming you haven't already) from your local immigration office. 3 forms to fill out, bring 2 passport photos, a TM.30 receipt, copy of bio page and copy of entry stamp plus 1900baht. (You can get your TM.30 receipt from the hotel you're staying at, you might not need it but it's better to have it in case they ask for it)

Go to immigration one day before pay 2000 baht get an extension for 30 days

Where will you be in 30 days from now?

Yes it will cost you 1900b

yes. 30-day extension. 1900 baht.

Yes. You have a visa exempt entry stamp, and this qualifies for one 30-day extension.

Go to your local immigration and apply. This is a general list of requirements, but each office requirements may vary.