Funny - people like me - stuck here in the Arctic that is the No. Central CA Coast always think the grass must always be greener in locales like yours. And though I've visited CR maybe 7 or 8 times, I have to admit exactly that - it's almost all been limited to Arenal, Dominical, Osa and Limon/Puerto Viejo - with only one trip out to Santa Teresa/Malpais and Hermosa 20 years ago - I'm almost afraid to know what's become of it, actually.
But I can imagine that with its more temperate, arid landscape, Guanacaste presents different challenges for nurserymen. Good luck on your quest - you sound like someone to look up the next time I head your way.