You need not register with any particular service if you don't want to. Registration is mainly used as a technique to obtain your information for future marketing.
You will need the services of a Realtor to see the property though. If you don't know a Realtor it is a good idea to ask friends and family who they have used in the past. This way you will receive and unbiased opinion from someone you trust.
Unfortunately, living on the coast does carry some extra costs. Mortgage companies will require you to carry all three policies...home, wind and flood. Shop around for home and wind insurance to find the best price. Flood insurance is regulated and won't vary from company to company to much.
Whether or not it is worth it is up to the individual. I love being able to walk along the beach every morning to the additional cost is well worth it.