Yes, that’s right — to obtain a pregnant male you have to order a mated pair and then specify in the "comments" section of the online order form that you want the male to be pregnant. Ocean Rider will then select a mated pair for you in which the male is already gravid when they pack your order for shipping. There is an extra charge for a pregnant male, which will be added on to the cost of your order (the last time I checked with Carol the additional charge for a gravid male was $30).
After you get your order confirmation, I would also telephone Ocean Rider to confirm that the special order for a pregnant male has been duly noted, and that they were able to comply with your request.
Ocean Rider’s policy is only to sell pregnant males as part of a mated pair because it is stressful and cruel to separate pair-bonded seahorses from their mates.
Best wishes with all your fishes!