The prices in
Antigua are very high - and if you have a
Budget Marine account don't try getting a discount at Budget Marine there, it doesn't
work.
From Antigua to St. Martin is just a short sail and the savings you will achieve for any high-ticket items are well worth the trip.
I shopped at Jolly Harbour (and then down in
English Harbour as well) when my
boat was stored there for the season and found some items at only slightly inflated prices; but overall sourcing things was difficult.