Does anyone know if it's legal to purchase 2-Way Radios (walkie talkies), Motorola's in particular.... or are they legal to bring in from the states?

I see them being sold in various places, and tourists carrying using them here in Bangkok.

Technically, unless they are approved by the Communications Ministry, they are illegal. Bringing them in would be a problem if stopped by Customs.

You can buy some Citizen band Radios in Thailand (as far as I can remember working on 220 MHz) very cheap.

Those are then fully legal.