Rayong Condo/apartment Prices/rises/selling

I have an opportunity to buy a brand new studio apartment in a very nice new block in Rayong, about 5 min motorcycle from the beach.

Prices range from 600,000 baht to 800,000 baht. (34 sq metres to 54 square metres).

My question is - how good a price for quality build, corner apartment, balcony, good swimming pool, new private school being built nearby, very popular with middle class Thai business folks and so on?

What expected return, i.e. how can I reliably find out how much property value in that vicinity might rise/fall in the few years/months ahead?

I have been told that the 34 square metre rents for 6,500+ baht per month - sounds small but it is Rayong of course.

How do I find out more concrete and reliable information and from those reading this what knowledge do you have that might help me?

Kind Regards.