There is a 3G signal on Condado it just depend on which jardine you are in, if you are in J1 to J5 then you should be ok getting the Orange signal. Obviously a Spanish one would be cheaper than using a UK one on roaming, but if they dont want to buy one?
If they have an unlocked mobile for email then just a Spanisg SIM would do, they could possibly use it in their dongle as well.
SIM cards are cheap, guess it depends on how much they will use it and what they want to pay.