I buy my steaks from the wet market where they sell the beef. Thais seem to classify their beef by "soft steaks" or "tough steaks". Only by the "soft" for steaks, the hard would be for stews, etc. I think the cost has been about 270/300 baht, have the seller trim off all of the gristle and most of the fat, At home season with salt and pepper and put into a lightly greased pan. Cook to desired doneness then remove and let rest for 5 or 10 minutes.
Of course, if you have time to cook it over charcoal on a grill the steak should turn out better. I cook my steaks medium-rare and don't use any bbq sauce.