Are you planning a trip to Murcia Spain? If so, you'll have more access to sights and natural surroundings if you hire a car. It will be easier and faster to get around and you won't be at the mercy of public transportation or bus and train schedules. You'll also have the opportunity to see things that can't be reached by trains and busses. A taxi driver is fine for around town hops but way too pricey for out of town trips. Renting a car is a much better option.
The cost of hiring a car in Murcia is very reasonable since it is a tourist destination and there are many car rental companies. If you divide the cost of rental and gas between fellow tourists then you're looking at even a better deal. To book a car use the internet to find a car and rate that will work for you. If you can't afford to rent a car the entire time then try to rent one for a few days so you can take in some of the outlaying sights. Don't wait until you arrive at the airport to book a car since there may not be one available or the cost can be more than double.
Murcia is an amazing city but there are several daytrips possible to neighboring cities and coastal towns. You shouldn't pass up the opportunity to see these fascinating parts of the region. A road trip can bring a whole different experience to touring especially if you're traveling with others.
Don't be nervous about driving in another country. You should make sure you understand the driving rules of Spain and it's a good idea to have an international drivers license. Your insurance will generally not cover you while driving in other countries so make sure you get full coverage which can greatly increase your rate but you'll still be better off hiring a car.
Along with car rentals, the internet is a useful tool for researching and booking hotels and flights for your vacation. There are travel websites that offer one stop shopping but keep in mind that some budget airlines can only be booked through their own website. There are also travel packages available that make booking even more convenient and in some cases more affordable. Hotels generally offer discounts during the week and during the off peak season (winter).