Wondering how long your new/potential lighting system will last? How low your lighting system lasts will heavily depend on the quality of the fixtures chosen.
A cheap, low-quality lighting system will likely last you around 1-3 years. The reason for this is that these cheap fixtures aren't designed to withstand snow, rain, heat, cold, or whatever else your climate has to throw at it. In most cases, the cost-effective fixtures, transformers, and kits found in big box stores are made to give instant gratification and not a lifetime's worth. If you’re looking for a quick fix or are happy to replace these fixtures yearly, these more affordable systems may be a great option for you.
High-quality landscape lighting fixtures are built to be as robust as can be - while still being stylish, of course. The higher price tag is often due to the durable metals and materials used to build the fixtures. For example, a cheaper system will likely be made of plastic, whereas a higher quality system will be made of some sort of metal with glass lenses. Plastic can get brittle, fade, leak, etc. and metals tend to hold their ground better. Metals such as copper and brass are naturally resistant to corrosion, so they won't rust or break down over time.
These higher-quality fixtures can last a lifetime if properly cared for (see How to Maintain Low Voltage Lighting Systems) and LED fixtures will only need bulb replacements every 3-5 years (as long as the bulb isn't integrated)
While any professional in the industry is going to recommend the higher quality fixtures, the choice is ultimately up to you, the homeowner. If you like the idea of a cheaper-up-front option, don't mind purchasing replacement fixtures, and can take the time/spend the money to have them replaced, the cheaper light fixtures can be a good option!
However, if you're planning the landscape lighting for your forever home and want your fixtures to last as long as you stay there, or if you want to increase the value of your home, high-quality systems are definitely the way to go.