There are numerous web sites for finding crew berths on boats. I suggest that you try to crew as much as possible before investing in a boat. You will learn about what you like and don't like about the various boats that you crew on. A personal favorite of mine is https://www.findacrew.net/
As you develop there are "seasons" and "places." Borrow Jimmy Cornell's World Cruising Routes
from the library to see what I mean. Examples - US to Europe - June/July; Europe to Caribbean - November/December. North America to Caribbean - October. There are big "rallies" of hundreds of boats that take this trip at the same time (e.g. departing Norfolk, VA for the Caribbean) and lots of other boats that don't want to pay to join the rally but are on the same schedule. With big concentrations of boats moving you have a better chance of finding a berth than you might at another time.
I know this will create controversy hence the rant warning. IMHO you will do better if you and your wife do not crew on the same boat. As a Captain I rarely take a couple on board. It is natural for one spouse to protect the other when the Captain is unhappy with something one of them has done or is trying to teach one of them some aspect of sailing. The dynamics can get very sticky and I have had a couple of bad experiences. So I suggest you try to crew on different boats - particularly in a rally you will meet in the end and can enjoy the land side together.
1) Don't repeat cruising grounds. If you have been to the BVI go somewhere else. The VI are very protected and beautiful cruising grounds but they are not going to give you the experience that you need to cruise the Caribbean.
2) If you only intend to cruise for 2 or 3 months per year don't buy a boat (unless you are very rich!) Dealing with the boat for the other 10 months will be a royal pain. Not to mention that recommissioning the boat after not being used for 10 months will eat into your cruising time. Boats live in a hostile environment - salt water. Lots of wear even when you are not using them.
3) Consider out of season cruising. There are lots of boats in the Caribbean just sitting around all hurricane season. You can rent them for a song. Yes, you might lose a few days to bad weather. But you can rent a boat for 30% or less of what it would cost in high season. You always have the option of coming back to the charter base and giving the responsibility for the boat to the charter company while you hang out in a hotel. Just don't pick September - the statistically worst month for hurricanes!
Hope this helps.