Often it is best if you have someone locally who can do them for you. When I lived in FL, CJ (Cynthia James) was about 2 miles from me and gave the screaming "local girl" deal and also I could easily get fitted. This time I had one of my suits (both 2 piece for BB) copied from one of my CJ suits by a local custom bikini shop. The night show (much fancier) suit was made by a girl who does lots of local figure girls' outfits. 3 days before my show I tried on the suit and the bottoms were too small - she was able to redo them and get them to me before the show!
Otherwise, you can check out any of the order sites, but probably best to go to one that you can get a personal recommendation for and order EARLY! Especially as the "competition season" starts up, it could be come an issue to get your suit on time.