The bus system is quite marvelous. The buses go out into the farthest reaches of the countryside, and within the city you pay only 3 pesos. Bus fare from Vallarta up into Bucerias is 10 pesos. The employees need to be able to get home. If you are not totally familiar with Vallarta, it would be a good idea to come down for a short visit to scope out all the areas and decide where you want to live.
Many people just move down here, end up staying in a hotel, and then looking for a place to rent.
This can be costly. You also need to keep in mind that rentals go up and down and become available with the seasons. This is especially true with the places downtown and close to downtown. Finding housing, reasonable or otherwise, between October through April can be frustrating and far from a rewarding experience. Again, the most important aspect is to determine where and how you want to live.