Sorry, I'm from the UK . They are quite hard to get hold of here too - I know that this online aquarium stockists occasionally have them so maybe if you e-mail them they will be able to advise you?
Not sure if you get the mag over there but in last months edition of practicle Fishkeeping a stockist wrote in to say that he has 50 'true' siamese algae eaters.
Let me know if you want me to dig the article out for you as it had a phone number on it so he may be able to tell you of other stockists over there??