Thanks for writing. Unfortunately I do not have seed sources outsides of North America. You might check some seed companies' websites to see if they will ship seeds to Argentina.
Do you have a seed source who would ship this type of watermelon seed to UK? My wife is in UK at the moment.
If your wife is in the UK, she may look there for a seed vendor that has what you want. That would probably be easier than find a North American vendor who is willing to ship internationally. There may even be seed exchanges in the UK. I'm sorry I cannot offer more information.