Arrived in PV Wednesday night, went to Zona Romantica Thursday morning, had a half-ounce within 30 minutes without even looking. Paid 700 pesos (about $42 US). Same Mexican brick weed I smoked tons of decades ago, but a little better quality. (He first wanted 1,500 pesos, I walked, he said 1,000, I said 700, he said 800, I stuck to the number. I would've paid the 800 but there's no fun in that, and negotiating is Mexican culture.)
I'd never advise someone to buy weed illegally, foreign or domestic. Unless you're in a place where weed is illegal, and want to smoke. Then you do you.